Nepenthes khasiana mediated synthesis of stabilized gold nanoparticles: Characterization and biocompatibility studies

• Nepenthes khasiana (NK) extract acts as a reducing agent in the synthesis of gold nanoparticles.
• Capping of gold nanoparticles by phytoconstituents of NK prevents aggregation.
• Biocompatibility of gold nanoparticles makes it fit for various biomedical applications.

The current study summarizes a unique green process for the synthesis of gold nanoparticles by simple treatment of gold salts with aqueous extract of Nepenthes khasiana (NK)—a red listed medicinal plant and its characterization. Study on the effect of different process parameters like temperature, pH and stirring on surface and stability characteristics has been demonstrated. Formation of GNPs was visually observed by change in color from colorless to wine red and characterized by UV-Visible spectroscopy, FT-IR spectroscopy, Zetasizer, X-RD, ICP-AES, SEM-EDAX, AFM and TEM. In vitro stability studies of gold colloidal dispersion in various blood components suggest that, NK mediated GNPs exhibit remarkable in vitro stability in 2% bovine serum albumin, 2% human serum albumin (HSA), 0.2 M histidine, and 0.2 M cysteine but unstable in 5% NaCl solution and acidic pH. Biocompatibility of NK stabilized GNPs against normal mouse fibroblasts (L929) cell lines revealed nontoxic nature of GNPs and thus provides exceptional opportunities for their uses as nanomedicine for diagnosis and drug therapy. The role of antioxidant phytochemicals (flavonoids and polyphenols) of NK extract in synthesis of biocompatible and stabilized GNPs was demonstrated by estimating total flavonoid content, total phenolic content and total antioxidant capacity of extract before and after formation of GNPs. Fast and easy synthesis of biocompatible GNPs possesses unique physical and chemical features which serve as an advantage for its use in various biomedical applications. The overall approach designated in the present research investigation for the synthesis of GNPs is based on all 12 principles of green chemistry, in which no man-made chemical other than the gold chloride was used.

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