Metal-enhanced fluorescence through conventional Ag-polyethylene glycol nanoparticles for cellular imaging

Area of Science:

• Nanotechnology
• Biomedical Imaging
• Materials Science

Background:

• Metal-enhanced fluorescence (MEF) offers potential for improving signal intensity in bioimaging.
• Silver nanoparticles (Ag NPs) are explored for their plasmonic properties to enhance fluorescence.
• Optimizing the interface between nanoparticles and fluorophores is crucial for efficient MEF.

Purpose of the Study:

• To investigate the use of silver nanoparticles (Ag NPs) functionalized with polyethylene glycol (PEG) for metal-enhanced fluorescence (MEF) in cellular imaging.
• To determine the optimal molecular weight of PEG as a spacer for maximizing MEF.
• To evaluate the performance of Ag-PEG6k NPs in enhancing fluorescence signals of Alexa Fluor 488 in mesenchymal stem cells.

Main Methods:

• Synthesis and characterization of Ag NPs with varying PEG molecular weights.
• Spectroscopic measurements of quantum yield enhancement in fluorescein solutions.
• Fluorescence imaging experiments using mesenchymal stem cells stained with Alexa Fluor 488 and treated with Ag-PEG6k NPs.

Main Results:

• Ag NPs with PEG of molecular weight 6000 g (Ag-PEG6k) demonstrated a 2-fold quantum yield enhancement in fluorescein.
• The fluorescence enhancement factor in cellular imaging increased with Ag-PEG6k NP concentration.
• Optimal conditions (243 ppb Ag-PEG6k NPs and 625 ppm Alexa Fluor 488) yielded an enhancement factor exceeding 4.

Conclusions:

• Ag-PEG6k NPs represent a novel and effective tool for metal-enhanced fluorescence in cellular imaging.
• PEGylation of Ag NPs with an optimal molecular weight is critical for efficient MEF.
• This approach significantly enhances fluorescence signals, with potential applications in high-sensitivity bioimaging.