Objective To prepare gold nanoparticles (GNPs) with good dispersibility and homogeneous size, and to evaluate their biocompatibility.

Methods Gold nanoparticles were prepared by using HEPES to reduce HAuCl₄, and ultraviolet spectroscopy (UV) and transmission electron microscopy (TEM) were employed to characterize the prepared Au samples. The toxic effect and dose-effect of gold nanoparticles on L-929 mouse fibroblasts were investigated by MTT method and intracellular reactive oxygen species (ROS) detection kits at 24, 48 and 72 hours of the test.

Results The volume ratio of HAuCl₄ (2.5×10^-5 mmol/L) to HEPES (1.0×10^-2 mmol/L) was 100:1. The gold nanoparticle solution prepared by boiling was red and translucent with good stability and dispersibility. The characteristic absorption band for UV spectrophotometry stands at 525 nm, the average diameter of spherical gold nanoparticles was 24 nm and the size distribution was narrow under TEM observation. The absorbance value between the experimental group and the negative control group was not significantly different (P > 0.05). The cell toxicity of GNPs at low concentration (≤20 μg/mL) and negative control group were graded as 0~1 degree. The level of ROS were negatively proportional to the concentration of GNPs in DMEM in a certain range of concentration.

Conclusion Gold nanoparticles (GNPs) prepared by this method was good at safety and biocompatibility with no evident cytotoxicity.