No abstract

No abstract

Atomically precise metal nanoclusters capped with small molecules like amino acids are highly favored due to their specific interactions and easy incorporation into biological systems. However, they are rarely explored due to the challenge of surface functionalization of nanoclusters with small molecules. Herein, we report the synthesis of a green-emitting (λex = 380 nm, λem = 500 nm), single-amino-acid (l-tryptophan)-scaffolded copper nanocluster (Trp-Cu NC) via a one-pot route under mild reaction conditions. The synthesized nanocluster can be used for the rapid detection of a heavy metal, silver (Ag­(I)), in the nanomolar concentration range in real environmental and biological samples. The strong green photoluminescence intensity of the nanocluster quenched significantly upon the addition of Ag­(I) due to the formation of bigger nanoparticles, thereby losing its energy quantization. A notable color change from light yellow to reddish-brown can also be observed in the presence of Ag­(I), allowing its visual colorimetric detection. Portable paper strips fabricated with the Trp-Cu NC can be reliably used for on-site visual detection of Ag­(I) in the micromolar concentration range. The Trp-Cu NC possesses excellent biocompatibility, making it a suitable nanoprobe for cell imaging; thus, it can act as an in vivo biomarker. The nanocluster showed a significant spectral overlap with anticancer drug doxorubicin and thus can be used as an effective fluorescence resonance energy transfer (FRET) pair. FRET results can reveal important information regarding the attachment of the drug to the nanocluster and hence its role as a potential drug carrier for targeted drug delivery within the human body.

Atomically precise metal nanoclusters capped with small molecules like amino acids are highly favoured due to their specific interactions and easy incorporation into biological systems. However, they are rarely explored due to the challenge in surface functionalization of nanocluster with small molecules. Herein, we report the synthesis of green emitting (λ_ex = 380 nm, λ_em = 500 nm) single amino acid (L-tryptophan) scaffolded copper nanocluster (Trp-Cu NC) via one-pot route under mild reaction conditions. The synthesized nanocluster can be used for the rapid detection of heavy metal (Ag(I)) in the nanomolar concentration range in real environmental and biological samples. The strong green photoluminescence intensity of the nanocluster quenched significantly upon addition of Ag(I) due to the formation of bigger nanoparticles, thereby losing its energy quantization. A notable colour change from light yellow to reddish brown can also be observed in the presence of Ag(I) allowing its visual colorimetric detection. Portable paper strips fabricated with Cu-Trp NC can be reliably used for on-site visual detection of Ag(I) in the micromolar concentration range. The Trp-Cu NC possesses excellent biocompatibility making them suitable nanoprobe for cell imaging, thus can act as an in-vivo biomarker. The nanocluster showed a significant spectral overlap with an anticancer drug doxorubicin, thus can be used as an effective FRET pair. FRET results can reveal important information regarding the attachment of the drug to the nanocluster and hence, its role as a potential drug carrier for targeted drug delivery within human body.

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.