Protein-mimicking nanoparticle (Protmin)-based nanosensor for intracellular analysis of metal ions

In this study, we designed and applied protein-mimicking nanoparticles (Protmin) as an intracellular nanosensor for in vivo detection of lead ions (Pb2+). Monodispersed gold nanoparticles (AuNPs) of 13 nm in diameter were modified using poly-adenine-tailed Pb2+ specific 8-17 DNAzyme to form a spherical and functional Protmin. Substrate strands modified with a fluorophore at the 5' end and a quencher at the 3' end were bound to DNAzyme. Pb2+ facilitated cleavage of DNAzyme to release the fluorophore-modified short strands to generate fluorescence. We observed rapid kinetics of the Protmin nanosensor, for which the typical assay time was 10 min. Further, we demonstrated the Protmin nanosensor could readily enter living cells and respond to Pb2+ in the intracellular environment. The broad of range of Protmin designs will be useful for advancing biological and medical applications.