The biocompatibility of polyaniline and polypyrrole: A comparative study of their cytotoxicity, embryotoxicity and impurity profile

Petr Humpolíček,Věra Kašpárková,Jiří Pacherník,Jaroslav Stejskal,Patrycja Bober,Zdenka Capáková,Katarzyna Anna Radaszkiewicz,Ita Junkar,Marián Lehocký

doi:10.1016/j.msec.2018.05.037

Abstract

Conducting polymers (CP), namely polyaniline (PANI) and polypyrrole (PPy), are promising materials applicable for the use as biointerfaces as they intrinsically combine electronic and ionic conductivity. Although a number of works have employed PANI or PPy in the preparation of copolymers, composites, and blends with other polymers, there is no systematic study dealing with the comparison of their fundamental biological properties. The present study, therefore, compares the biocompatibility of PANI and PPy in terms of cytotoxicity (using NIH/3T3 fibroblasts and embryonic stem cells) and embryotoxicity (their impact on erythropoiesis and cardiomyogenesis within embryonic bodies). The novelty of the study lies not only in the fact that embryotoxicity is presented for the first time for both studied polymers, but also in the elimination of inter-laboratory variations within the testing, such variation making the comparison of previously published works difficult. The results clearly show that there is a bigger difference between the biocompatibility of the respective polymers in their salt and base forms than between PANI and PPy as such. PANI and PPy can, therefore, be similarly applied in biomedicine when solely their biological properties are considered. Impurity content detected by mass spectroscopy is presented. These results can change the generally accepted opinion of the scientific community on better biocompatibility of PPy in comparison with PANI.

Highlights

The impact of bioelectricity on physiological processes can be observed either on the level of individual cells, e.g., the stem cell differentiation [1] and cell movement [2], or on the level of tissues, e.g., the physiology of electro-sensitive tissues or wound healing [3]
Though polyaniline (PANI) and polypyrrole (PPy) are the most studied conducting polymers, and there are a number of studies dealing with their preparation, characterization, and physico-chemical properties, the works which focus on their comparison are scarce as regards their chemistry [5,6] and especially their biological properties [7,8]
PANI was synthetized using the oxidation of aniline hydrochloride with ammonium persulfate according to the respective IUPAC protocol [16], and PPy was prepared via the oxidation of pyrrole with iron(III) chloride, which is the oxidant of first choice in the preparation of this polymer (Fig. 1) [21,22]

Summary

Introduction

The impact of bioelectricity on physiological processes can be observed either on the level of individual cells, e.g., the stem cell differentiation [1] and cell movement [2], or on the level of tissues, e.g., the physiology of electro-sensitive tissues or wound healing [3]. Though polyaniline (PANI) and polypyrrole (PPy) are the most studied conducting polymers, and there are a number of studies dealing with their preparation, characterization, and physico-chemical properties, the works which focus on their comparison are scarce as regards their chemistry [5,6] and especially their biological properties [7,8]. Both PANI and PPy have been used extensively for the preparation of composites with other materials and subsequently tested in terms of their biological properties, such as their in vivo capacities to cause reactions in tissues [9,10]. This lack of knowledge is critical if biologically-oriented applications are to be considered

Methods

Results

Conclusion