Cobalt nanoparticles as novel nanotherapeutics against Acanthamoeba castellanii

Abstract

Background Species of Acanthamoeba are facultative pathogens which can cause sight threatening Acanthamoeba keratitis and a rare but deadly brain infection, granulomatous amoebic encephalitis. Due to conversion of Acanthamoeba trophozoites to resistant cyst stage, most drugs are found to be ineffective at preventing recurrence of infection. This study was designed to test the antiacanthamoebic effects of different cobalt nanoparticles (CoNPs) against trophozoites and cysts, as well as parasite-mediated host cell cytotoxicity. Methods Three different varieties of CoNPs were synthesized by utilizing hydrothermal and ultrasonication methods and were thoroughly characterized by X-ray diffraction and field emission scanning electron microscopy. Amoebicidal, encystation, excystation, and host cell cytopathogenicity assays were conducted to study the antiacanthamoebic effects of CoNPs. Results The results of the antimicrobial evaluation revealed that cobalt phosphate Co 3 (PO 4 ) 2 hexagonal microflakes, and 100 nm large cobalt hydroxide (Co(OH) 2 ) nanoflakes showed potent amoebicidal activity at 100 and 10 µg/ml against Acanthamoeba castellanii as compared to granular cobalt oxide (Co 3 O 4 ) of size 35–40 nm. Furthermore, encystation and excystation assays also showed consistent inhibition at 100 µg/ml. CoNPs also inhibited amoebae-mediated host cell cytotoxicity as determined by lactate dehydrogenase release without causing significant damage to human cells when treated alone. Conclusions To our knowledge, these findings determined, for the first time, the effects of composition, size and morphology of CoNPs against A. castellanii . Co 3 (PO 4 ) 2 hexagonal microflakes showed the most promising antiamoebic effects as compared to Co(OH) 2 nanoflakes and granular Co 3 O 4 . The results reported in the present study hold potential for the development of antiamoebic nanomedicine.

Tannic acid-modified silver nanoparticles enhance anti-Acanthamoeba activity without increasing cytotoxicity of the contact lens solutions

“…Guanabenz, a drug already approved for hypertension that crosses the blood − brain barrier, conjugated with AuNPs and AgNPs showed signi cant anti-amoebic activity against both A.castellanii and Neagleria fowleri. Signi cant reduction in the host cell cytopathogenicity, especially for silver nanoconjugates, was revealed and associated with negligible cytotoxicity against human cells [47].…”

Biogenic Metal Nanoparticles: A New Approach to Detect Life on Mars?

“…CoNPs have been used for their antimicrobial capacity, e.g., against Acanthamoeba castellanii, a facultative pathogen that can cause several diseases, some with high associated rates of mortality and morbidity, and for which there is no known drug available [16].…”

Effects of Shape and Size of Cobalt Phosphate Nanoparticles against Acanthamoeba castellanii

“…phosphate microflakes (Co3(PO4)2), and cobalt hydroxide nanoflakes (Co3(OH)2), were studied, and cobalt phosphate microflakes were found to be the most effective anti-acanthamoebic agent [34].…”

“…The cobalt (II)-lapachol complex has also been proven to have anti-acanthamoebic activity [33]. Previously, the anti-acanthamoebic effects of three types of cobalt nanoparticles, which include cobalt oxide nanograins (Co 3 O 4 ), cobalt phosphate microflakes (Co 3 (PO 4 ) 2 ), and cobalt hydroxide nanoflakes (Co 3 (OH) 2 ), were studied, and cobalt phosphate microflakes were found to be the most effective anti-acanthamoebic agent [34].…”