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Synthesis of Near-Infrared Emitting Gold Nanoclusters for Biological Applications
Published on: March 22, 2020
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Cancer Cell Imaging Using in Situ Generated Gold Nanoclusters
Shyamtanu Chattoraj1, Md Asif Amin1, Saswat Mohapatra2
1Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata, 700 032, India.
Summary
Fluorescent gold nanoclusters (Au-NCs) effectively bio-image cancer cells, showing higher uptake due to increased glutathione levels. These non-toxic Au-NCs offer a promising tool for cancer diagnostics.
Area of Science:
- Nanotechnology
- Biomedical Imaging
- Cancer Research
Background:
- Gold nanoclusters (Au-NCs) are emerging as fluorescent probes for bio-imaging.
- Understanding their behavior within different cell types is crucial for diagnostic applications.
- Cancer cells often exhibit altered metabolic profiles, potentially affecting nanoparticle uptake.
Purpose of the Study:
- To investigate the in situ generation and bio-imaging capabilities of fluorescent Au-NCs in human cancer cells.
- To compare Au-NC uptake and fluorescence in cancer versus non-cancer cells.
- To characterize the properties and safety of the Au-NCs for potential biomedical use.
Main Methods:
- In situ generation of fluorescent Au-NCs using a room-temperature ionic liquid (RTIL) conjugate ([pmim][AuCl4]).
- Confocal microscopy for bio-imaging of lung (A549), breast (MCF7), and colon (HCT116) cancer cells, and non-cancer cells (WI38, MCF10A).
- Time-resolved confocal microscopy and fluorescence correlation spectroscopy (FCS) for lifetime and size determination.
- Matrix-assisted laser desorption ionization (MALDI) mass spectrometry for structural analysis.
- Cytotoxicity studies to assess safety.
Main Results:
- Significantly higher accumulation (20-40 times) of Au-NCs observed in cancer cells compared to non-cancer cells.
- Higher glutathione (GSH) levels in cancer cells are correlated with increased Au-NC uptake.
- Au-NCs exhibited fluorescence maxima at 490-530 nm within cancer cells.
- Characterization confirmed GSH-capped Au-NCs with a core structure (Au8-13) and a nanosecond fluorescence lifetime (1-3 ns).
- FCS indicated an Au-NC size of approximately 1-2 nm.
- The RTIL conjugate ([pmim][AuCl4]) demonstrated non-toxic properties.
Conclusions:
- In situ generated fluorescent Au-NCs are effective and selective bio-imaging agents for human cancer cells.
- Differential uptake is linked to higher intracellular glutathione levels in cancer cells.
- The characterized Au-NCs are non-toxic, suggesting their potential for targeted cancer imaging and diagnostics.
