Fig. 4

Surface potential of A HNTs-Ag NPs and B HNTs-FA-Ag NPs was measured by Malvern Zetasizer_nanoZS. The presence of folic acid increases the negative charge on NPs. C Shows the better solubility of HNTs-FA-Ag NPs in water compared to HNTs-Ag NPs, so that in a short time, a significant amount of it penetrated the aqueous solvent