Free-living amoebae include Acanthamoeba castellanii and Naegleria fowleri that are opportunistic protozoa responsible for life-threatening central nervous system infections with mortality rates over 90%. The rising number of cases and high mortality rates are indicative of the critical unmet need for the development of efficient drugs in order to avert future deaths. In this study, we assess the anti-amoebic capacity of a conducting polymer nanocomposite comprising polyaniline (PANI) and hexagonal boron nitride (hBN) against A. castellanii and N. fowleri. We observed significant amoebicidal and cysticidal effects using 100 μg/mL PANI/hBN (P < 0.05). Further, the nanocomposite demonstrated negligible cytotoxicity toward HaCaT and primary human corneal epithelial cells (pHCECs). In evaluating the mode of inhibition of A. castellanii due to treatment with PANI/hBN, increased intracellular reactive oxygen species (ROS) was measured and scanning microscopy visualized the formation of pores in the amoebae. Overall, this study is suggestive of the potential of the PANI/hBN nanocomposite as a promising therapy for amoeba infections.
Primary amoebic meningoencephalitis and granulomatous amoebic encephalitis are distressing infections of the central nervous system caused by brain-eating amoebae, namely, Naegleria fowleri and Acanthamoeba spp., respectively, and present mortality rates of over 90%. No single drug has been approved for use against these infections, and current therapy is met with an array of obstacles including high toxicity and limited specificity. Thus, the development of alternative effective chemotherapeutic agents for the management of infections due to brain-eating amoebae is a crucial requirement to avert future mortalities. In this paper, we synthesized a conducting polymer-based nanocomposite entailing polyaniline (PANI) and molybdenum disulfide (MoS2) and explored its anti-trophozoite and anti-cyst potentials against Acanthamoeba castellanii and Naegleria fowleri. The intracellular generation of reactive oxygen species (ROS) and ultrastructural appearances of amoeba were also evaluated with treatment. Throughout, treatment with the 1:2 and 1:5 ratios of PANI/MoS2 at 100 μg/mL demonstrated significant anti-amoebic effects toward A. castellanii as well as N. fowleri, appraised to be ROS mediated and effectuate physical alterations to amoeba morphology. Further, cytocompatibility toward human keratinocyte skin cells (HaCaT) and primary human corneal epithelial cells (pHCEC) was noted. For the first time, polymer-based nanocomposites such as PANI/MoS2 are reported in this study as appealing options in the drug discovery for brain-eating amoebae infections.