A facile method for synthesis of gold nanotubes and their toxicity assessment

•Partially green approach for synthesis of gold nanotubes is presented.•In vitro cytotoxicity assessment of synthesized AuNTs.•Comparative cytotoxicity assessment of biogenic and chemically synthesized NTs.•NTs synthesized by partially green approach were less toxic.

Gold nanotubes hold great potential for various biomedical applications such as gene transfer, tissue engineering, image processing, biosensors, in nanopore sequencing and hence they need to be non-toxic and biocompatible. In this context, we present a partially green approach for gold nanotube synthesis and determine their toxicity using in vitro assays. The gold nanotubes were synthesized using sodium sulphate nanowires as sacrificial template on which gold nanoparticles produced in Escherichia coli DH5α were deposited to get a tubular structure. The gold nanoparticles, sodium sulphate nanowires and gold nanotubes were characterized using transmission electron microscopy. The toxicity of gold nanotubes was determined using Trypan blue assay and lactate dehydrogenase (LDH) assay. The cytotoxicity profile of these nanotubes was also compared with the cytotoxicity profile of nanotubes synthesized by complete chemical approach. Results showed that the use of biogenic gold nanoparticles in preparing the nanotubes has significantly decreased the cytotoxicity as compared to nanotubes prepared using chemical method. The % cytotoxicity with trypan blue assay and LDH assay ranges from 8.2 to 33% and 8.8 to 31.2%, respectively with increasing concentration of gold nanotubes (0.1–10 mg/ml) for biogenic nanotubes.