Unveiling the photoluminescence dynamics of gold nanoclusters with FCS and FLCS

Gold nanoclusters (AuNCs) have garnered significant attention for their unique photoluminescent properties, holding large promise across a spectrum of applications. However, our understanding of their rapid photodynamics has remained elusive due to limitations posed by ensemble-averaged spectroscopy techniques.

To address this knowledge gap, we use fluorescence correlation spectroscopy (FCS) to delve into the photoluminescence dynamics of colloidal Au₁₈(SG)₁₄ nanoclusters. We address questions surrounding blinking behavior, brightness per nanocluster, and the influence of excitation power and ligands in a recent Nanoscale Advances publication. Notably, our findings reveal the distinctive quantum nature of the photoluminescence process, establishing each AuNC as an individual quantum source with a single emitting center.

In a second study published in BBA General Subjects, we combine water-soluble Au₁₈(SG)₁₄ gold nanoclusters with two organic fluorescent dyes, Alexa Fluor 647 and CF640R, presenting a ternary mixture of fluorescent emitters with nearly identical emission spectra. This work extends the capabilities of fluorescence lifetime correlation spectroscopy (FLCS) for the first time to a ternary mixture, surpassing traditional multiplexing limitations associated with distinct fluorescent dyes across the visible spectrum. Additionally, we demonstrate the suitability of gold nanoclusters for FLCS multiplexing applications, highlighting their microsecond lifetime and stable emission characteristics as valuable additions to the FLCS probe repertoire.
Our research contributes to the understanding of AuNC photodynamics, fostering the development of AuNCs in biosensing and imaging applications where single emitter resolution matters.

Both papers published open access. Open science matters.