Enhanced detection using stable isotope enriched 65Cu doped ferrite nanoparticles for tracing studies

⁶⁵Copper stable isotope doped ferrite nanoparticles with two dopant concentrations were prepared by a co-precipitation method for conducting biomedical experiments at environmentally relevant concentrations. The synthesized (⁶⁵Cu<inf>x</inf>Fe<inf>1-x</inf>Fe<inf>2</inf>O<inf>4</inf>) nanoparticles were of 30 ± 7 nm in size and the VSM measurements showed a magnetic moment of 30 emu/g of un-doped ferrite particles at 310 K. The amount of ⁶⁵Cu doped in the ferrite nanoparticles were calculated using ICP-MS. Cytocompatibility studies were performed through cellular toxicity assays on WRL68 liver cell line. MTT and ROS assay demonstrated cell viability in an order of Fe<inf>3</inf>O<inf>4</inf>>⁶⁵Cu<inf>0.088</inf>Fe<inf>2.085</inf>O<inf>4</inf>>⁶⁵Cu<inf>0.143</inf>Fe<inf>3.31O4</inf>. The cytocompatibility and magnetic measurement data set indicate that by doping a small amount of copper, the ferrite nanoparticles can retain their magnetic properties and the cytocompatibility is not severely compromised. ⁶⁵Cu<inf>0.088</inf>Fe<inf>2.085</inf>O<inf>4</inf> (d<inf>1</inf>-Fe<inf>3</inf>O<inf>4</inf>) and ⁶⁵CuO nanoparticles were used for tracing experiments, wherein, even at a lower exposure concentration of 0.5 μg/mL, ⁶⁵Cu can be detected in the media even when the copper background concentration is high. The results indicate the ability to perform biological studies at low exposure concentrations with enhanced detection ability. The proposed technique shows that isotope enriched copper doped ferrite can serve the purpose of quantifiable traceable nanocarriers.