Metal-Enhanced Fluorescent Carbon Quantum Dots via One-Pot Solid State Synthesis for Cell Imaging

Area of Science:

• Materials Science
• Nanotechnology
• Biophotonics

Background:

• Carbon quantum dots (CQDs) and gold nanoparticles (AuNPs) are nanomaterials with unique optical properties.
• Metal-enhanced fluorescence (MEF) is a phenomenon where proximity to metal nanoparticles amplifies fluorescence.
• Solid-state synthesis offers advantages in terms of efficiency and environmental impact.

Purpose of the Study:

• To develop a facile one-pot solid-state synthesis for N-doped CQDs/gold hybrid nanomaterials.
• To investigate the mechanism of metal-enhanced fluorescence (MEF) in CQDs-AuNPs hybrid systems.
• To optimize the CQDs-AuNPs hybrid for maximum fluorescence enhancement and evaluate their potential in bioimaging.

Main Methods:

• One-pot solid-state synthesis of N-doped CQDs/AuNPs hybrid nanomaterials.
• Systematic variation of gold precursor concentration to study its effect on fluorescence.
• Characterization of synthesized materials using spectroscopic and microscopic techniques.
• Evaluation of MEF and fluorescence resonance energy transfer (FRET) effects.
• In vitro cell imaging experiments using human dermal fibroblasts and A549 lung epithelial cells.
• Cytotoxicity assessment of the synthesized hybrid materials.

Main Results:

• A facile one-pot solid-state synthesis method for N-doped CQDs/AuNPs hybrids was successfully developed.
• A significant 10³-fold enhancement in photoluminescence intensity was observed with the addition of a small amount of gold salt, attributed to MEF.
• Increased gold concentration led to fluorescence quenching, likely due to fluorescence resonance energy transfer (FRET).
• Optimal CQDs-AuNPs hybrid composition was identified, exhibiting strong visible light emission under 460 nm excitation.
• The synthesized hybrid materials demonstrated successful application in imaging various cell types.
• Dose-dependent cytotoxicity studies confirmed the non-toxic nature of the CQDs-AuNPs hybrid structures.

Conclusions:

• The developed solid-state synthesis is an efficient route for creating CQDs-AuNPs hybrids with tunable fluorescence properties.
• MEF plays a crucial role in enhancing the photoluminescence of CQDs when hybridized with AuNPs.
• The synthesized CQDs-AuNPs hybrids are promising, non-toxic fluorescent probes for advanced bioimaging applications.