Novel dual labelled nanoprobes for nanosafety studies: Quantification and imaging experiment of CuO nanoparticles in C. elegans

Metal oxide nanoparticles have been extensively studied for their toxicological impacts. However, accurate tracing/quantification of the nanomaterials and their biological responses are difficult to measure at low concentrations. To overcome the challenge, we developed a dual-labelling technique of CuO nanoparticles with a stable isotope of Cu-65, and with rhodamine dye. In vivo experiments on C. elegans were performed using natural feeding of Rhodamine B isothiocyanate-(3 aminopropyl) triethoxysilane functionalized (CuO)-Cu-65 nanoprobes (RBITC-APTES@(CuO)-Cu-65) (size = 7.41 +/- 1 nm) within the range of Predicted Environmental Concentration (PEC) of CuO nanoparticles in soil and sediments. Fluorescence emission (570 nm) was detected in the lumen of the intestine and the pharynx of C. elegans with no impact of nanoparticle exposure on the brood size and life span of worms. The ingested fluorescent labelled RBITC-APTES@(CuO)-Cu-65 nanoprobes did not enter the reproductive system and were distributed in the alimentary canal of C. elegans. Strong fluorescent signals from the ingested RBITC-APTES@(CuO)-Cu-65 nanoprobes were achieved even after 24 h of exposure demonstrating the high stability of these nanoprobes in vivo. The net accumulation measured of Cu-65 in C. elegans after background subtraction was 0.001 mu g mg(-1) (3.52 %), 0.005 mu g mg(-1) (1.76 %) and 0.024 mu g mg(-1) (1.69 %) for an exposure concentration of 0.0284 mu g mg(-1), 0.284 mu g mg(-1), and 1.42 mu g mg(-1) of Cu-65, respectively. Using C. elegans as a model organism, we demonstrated that RBITC-APTES tagged (CuO)-Cu-65 nanoparticles acted as novel nanoprobes for measuring the uptake, accumulation, and biodistribution through quantification and imaging the nanoprobes at a very low exposure concentration ((CuO)-Cu-65 concentration: 0.033 mu g mg(-1)).

Automated summary

This study developed a dual-labelling technique for CuO nanoparticles, allowing for the measurement of uptake, accumulation, and biodistribution at low concentrations. The experiment demonstrated the stability and distribution of the nanoprobes in vivo, indicating their potential as novel nanoprobes for toxicological studies.