Nano-biohybrids of engineered nanoclays and natural extract for antibacterial agents

Abstract We have prepared nano-biohybrids between engineered nanoclays and antibacterial natural extract. Agrimonia pilosa Ledeb (AP) was treated with either hot water or ethanol to obtain two kinds of extract, and we found that water extract was more efficient in bacterial inhibition. Pore volume and specific surface area of three clays, such as illite, scoria and hydrotalcite, were engineered with acid or heat, before hybridization. Nano-biohybridization was carried out with engineered nanoclays powder and extract solution. According to thermogravimetry and dry weight method, it was determined that extract content in hybrid were between 11.6 and 39.5%. X-ray diffraction patterns showed that the crystal structure of engineered nanoclay was preserved after hybridization. Scanning electron microscopy, extract content analyses and zeta potential measurement suggested that the surface of nanoclays were evenly and thoroughly covered with extract moiety with a few molecular layers. Differential thermal analyses on hybrid indicated broad and lowered combustion temperature of extract components in hybrids compared with extract only, suggesting possible molecular rearrangement of extract moiety on nanoclay surface. We then evaluated bacterial colony forming inhibition of extract and nano-biohybrids of which result indicated higher antibacterial efficacy of hybrids than extract itself.