Abstract
Gold nanoparticles (AuNPs) are used for a number of imaging and therapeutic applications in east and western part of the world. For thousands of years, the traditional Indian Ayurvedic approach to healing involves the use of incinerated gold ash, prepared with a variety of plant extracts and minerals depending on the region. Here, we describe the characterization of incinerated gold particles (IAuPs) in HeLa (human cells derived from cervical cancer) and HFF-1 (human foreskin fibroblast cells) in comparison to synthesized citrate-capped gold nanoparticles (AuNPs). We found that while individual IAuP crystallites are around 60 nm in size, they form large aggregates with a mean diameter of 4711.7 nm, some of which can enter cells. Fewer cells appeared to have IAuPs compared to AuNPs, although neither type of particle was toxic to cells. Imaging studies revealed that IAuPs were in vesicles, cytosol, or in the nucleus. We found that their nuclear accumulation likely occurred after nuclear envelope breakdown during cell division. We also found that larger IAuPs entered cells via macropinocytosis, while smaller particles entered via clathrin-dependent receptor-mediated endocytosis.
Highlights
Gold nanoparticles (AuNPs) are used for a number of imaging and therapeutic applications including diagnosis and treatment of cancers[1, 2]
Since the preparation and composition of Swarna Bhasma IAuPs can vary depending on the geographical region, the IAuPs used in this study were characterized in vitro[15,16,17,18,19]
Dynamic Light Scattering (DLS) analysis revealed that IAuPs have a broad range in size with a mean diameter of 4711.7 nm (Fig. 2B)
Summary
Gold nanoparticles (AuNPs) are used for a number of imaging and therapeutic applications including diagnosis and treatment of cancers[1, 2]. Gold derived Ayuverdic medicine is called Swarna Bhasma (gold ash)[4, 10,11,12], and testing their localization, entry and impact on human cells in comparison to chemically synthesized AuNPs will be the focus of this study. The composition and size of IAuPs from different pharmaceutical companies is variable They contain a range of compounds and elements, including heavy metals[17,18,19], derived from herbal extracts typically used for medicinal purposes. There are reports of using protein tags with specific amino acid sequences known to mediate transport into the nucleus[32] or mitochondria[33, 34] It is not clear how these tags have accessibility to the protein complexes that recognize them when the particles are retained in vesicles, when they are in lysosomes or autophagosomes. Very small particles may not require tags to pass through the nuclear pores, or outer mitochondrial membrane
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