Strong anti-kinetoplastid activity of silver nanoparticle-coated biochar

Neglected tropical diseases including Chagas disease, also known as American trypanosomiasis and leishmaniasis remains a serious health problem in several endemic. To address this medical problem, much has been done in the past 15 years to design nanomaterials with effective anti-kinetoplastids activity, particularly those nanomaterials based on gold and silver nanoparticles. Herein, we describe a simple method to prepare silver-loaded biochar by pyrolysis of silver nitrate-impregnated agrowaste powder (from olive stones). The resulting Biochar@Ag was prepared at 400 °C for 15 minutes only and the yield was found to be 36.5 %. The supported metallic Ag nanoparticles have triangular shape in the nanoscale regime (< 100 nm) and a loading of 7.85 mmol per gram of Biochar@Ag. The Biochar@Ag showed promising antiparasitic activity against promastigotes stage of L. donovani, L. amazonensis and epimastigotes of T. cruzi with and IC50 of 9.942 ± 0.900 ppm; 14.555 ± 1.035 ppm and 12.154 ± 0.206 ppm, respectively. From the above, this work conclusively demonstrates that slow pyrolysis is a unique thermochemical approach to valorize agrowastes into highly effective anti-kinetoplastid silver-loaded biochar with remarkably low cytotoxicity towards murine macrophages.