Graphene oxide functionalized with ethylenediamine triacetic acid for heavy metal adsorption and anti-microbial applications

The development of functionalized nanomaterials that leads to multi-functionality, such as the ability to adsorb heavy metals coupled with anti-microbial properties is very attractive for diverse applications. The present study evaluated for the first time the antimicrobial activity of graphene oxide silanized with N-(trimethoxysilylpropyl) ethylenediamine triacetic acid (GO-EDTA) against Gram-negative, Cupriavidus metallidurans CH4, and Gram-positive bacteria, Bacillus subtilis, as well as its cytotoxicity to human corneal epithelial cell line hTCEpi. The results show that GO-EDTA has improved anti-microbial properties when compared to graphene oxide (GO) alone, with 92.3 ± 10% and 99.1 ± 1.3% cell inactivation of B. subtilis and C. metallidurans, respectively. Bacterial inactivation was attributed to an oxidative stress mechanism towards the cells. No cytotoxicity was observed towards human corneal epithelial cell lines hTCEp after 24 h exposure to GO-EDTA, suggesting that this nanomaterial has the potential for applications that have human exposure. This work also evaluated GO-EDTA's adsorption capacity for two heavy metals, Cu2+ and Pb2+ at different concentrations, varying pH and contact time. The maximum adsorption capacity of the GO-EDTA was determined to be 454.6 mg g−1 and 108.7 mg g−1 for Pb2+ and Cu2+, respectively, exceeding the capacity of traditional adsorbent materials, such as activated carbon.