Lysozyme protected Cu Nano-Cluster: A Photo Switch for the Selective Sensing of Iron (Fe2+)

Protein capped metal nanoclusters gained a lot of recent attention due to their wide range of applications. Here we successfully synthesized a stable, biocompatible lysozyme protected Cu nanocluster (Lys-Cu NC) using an optimized green one-pot protocol under aqueous condition at room temperature. The nanocluster showed a strong photoluminescence intensity (λex = 365 nm, λem = 430 nm) which can be significantly and selectively quenched (off) by Fe2+ ions. Upon addition of NaOH the initial photoluminescence intensity can be recovered completely (on) thereby making the nanocluster a suitable candidate for a photo switch that can be reliably reused for the selective and sensitive detection of Fe2+ ions in the nanomolar (detection limit ~2.5 nM) concentration range. The photoluminescence intensity is also sensitive towards temperature indicating that it can be used as a temperature sensor in different biological systems. It can also be used as an excellent nanoprobe for cell imaging studies.