Protein-directed synthesis of pH-responsive red fluorescent copper nanoclusters and their applications in cellular imaging and catalysis

Abstract

The development of functional copper nanoclusters (Cu NCs) is becoming increasingly widespread in consumer technologies due to their applications in cellular imaging and catalysis. Herein, we report a simple protein-directed synthesis of stable, water-soluble and fluorescent Cu NCs, using BSA as the stabilising agent. Meanwhile, in this study, hydrazine hydrate (N₂H₄·2H₂O) was used as the reducing agent. N₂H₄·2H₂O was a mild reducing agent suggesting that all processes could be operated at room temperature. The as-prepared Cu NCs showed red fluorescence with a peaking center at 620 nm (quantum yield 4.1%). The fluorescence of the as-prepared BSA-Cu NCs was responsive to pH in that the intensity of fluorescence increased rapidly by decreasing the pH from 12 to 6. Besides, with an arresting set of features including water-dispersibility, red fluorescence, good biocompatibility, surface-bioactivity and small size, the resultant BSA-Cu NCs could be used as probes for cellular imaging and catalysis. In this study, CAL-27 cells and the reaction of oxidation of styrene are used as models to achieve fluorescence imaging and elucidate the catalytic activity of the as-prepared BSA-Cu NCs.

Nanoclusters prepared from a silver/gold alloy as a fluorescent probe for selective and sensitive determination of lead(II)

“…3). BSA-capping fluorescent metal NCs displayed good dispersion and high stability in aqueous phase [26,27]. Especially, BSA has a much-stronger affinity toward metal ions, including Pb 2+ , which is important for practical applications in ion detection.…”

“…As-prepared Ag/Au alloy NCs were protected by bovine serum albumin (BSA) which could work as an important scaffold to prevent NCs from growing large NPs [25]. More importantly, NCs stabilized by BSA exhibited good dispersion and high stability in aqueous solution [26,27]. These advantages illustrated that the resultant alloy NCs were promising fluorescent probes for detection of heavy-metal ions.…”

A convenient purification method for silver nanoclusters and its applications in fluorescent pH sensors for bacterial monitoring

“…Until now, extensive studies have concentrated on the synthesis of luminescent and water-soluble metal nanoclusters using various types of templates or stabilizing agents such as peptides , proteins (Wang et al, 2014a), DNA (Copp et al, 2014), polymers (Shang and Dong, 2008), dendrimers (Tanaka et al, 2011) and thiols (Wu et al, 2009). Experimentally, largely excessive templates were required to stabilize nanoclusters or reduce metal salts to form template-protected metal clusters.…”

In-situ green synthesis of highly active GSH-capped Pt-Au-Ag-hybrid nanoclusters

“…These characteristics partly originate from their large specific surface area, which is due to their small sizes [9][10][11][12][13][14][15]. Through stabilization of protective agents, it has been shown that the stability and fundamental properties of noble metal NPs can be significantly enhanced [16,17].…”