An Unconventional Approach Imparting Structurally Well-Defined Photoluminescent Gold Clusters With Water Solubility

Area of Science:

• Nanotechnology
• Materials Science
• Biochemistry

Background:

• Water-soluble, photoluminescent gold clusters are crucial for biological applications.
• Current methods for achieving water solubility in gold clusters can be limited.
• Atomically precise gold clusters offer unique photophysical properties.

Purpose of the Study:

• To develop a new surface modification strategy to impart water solubility to atomically precise gold clusters.
• To investigate the impact of dimethoxymethyl functionalization on the photoluminescence and structure of gold clusters.
• To evaluate the potential of these water-soluble gold clusters for cellular imaging.

Main Methods:

• De novo surface modification of pyridyl groups in gold clusters with dimethoxymethyl (formaldehyde dimethyl acetal) groups.
• Synthesis and characterization of functionalized gold clusters using single-crystal X-ray diffraction (SCXRD) and ESI-MS.
• Photoluminescence quantum yield (QY) measurements in aqueous solution.
• Live cell imaging studies to assess cellular uptake and localization.

Main Results:

• Significant enhancement of water solubility in gold clusters functionalized with dimethoxymethyl groups.
• Preservation of molecular structure and intense photoluminescence (PL) in the modified clusters.
• Achieved a high quantum yield (QY) of 32.7% for a representative cluster (2a) in water.
• Demonstrated successful cellular uptake and nucleolar accumulation of cluster 2a in living cells.
• Confirmed the universality of the approach across different gold cluster types (C@Au6Ag2-, C@Au6Ag4-, and C@Au6-).

Conclusions:

• The dimethoxymethyl surface modification is an effective and versatile strategy for creating water-soluble atomically precise gold clusters.
• These water-soluble gold clusters retain their desirable photoluminescent properties.
• The functionalized clusters show promise as imaging agents for biological systems, particularly for nuclear and nucleolar imaging.
• This approach provides a practical pathway for advancing the use of metal clusters in bioimaging and related fields.