Efficient two-photon luminescence for cellular imaging using biocompatible nitrogen-doped graphene quantum dots...

Area of Science:

• Nanomaterials Science
• Biomedical Imaging
• Bioconjugation Chemistry

Background:

• Two-photon bioimaging requires stable contrast agents with high signal-to-noise ratios.
• Conventional contrast agents often require high excitation power, limiting imaging depth and potentially causing phototoxicity.
• Developing novel nanomaterials with enhanced optical properties is crucial for advanced bioimaging applications.

Purpose of the Study:

• To develop and characterize nitrogen-doped graphene quantum dots (N-GQDs) conjugated with targeting antibodies for two-photon bioimaging.
• To evaluate the two-photon properties, stability, and imaging performance of the N-GQD-based contrast agent.
• To assess the potential of N-GQD-PEI-PSS-AbEGFR as an effective contrast agent for deep-tissue, three-dimensional imaging.

Main Methods:

• Synthesis and characterization of nitrogen-doped graphene quantum dots (N-GQDs).
• Conjugation of N-GQDs with polyethylenimine (PEI), polystyrene sulfonate (PSS), and anti-epidermal growth factor receptor (AbEGFR) antibody.
• Evaluation of two-photon excitation (TPE) properties, including fluorescence intensity, brightness, and signal-to-noise ratio.
• Assessment of imaging performance in deep, three-dimensional biological samples using ultra-low TPE power.

Main Results:

• The synthesized N-GQD-PEI-PSS-AbEGFR nanomaterials exhibited excellent two-photon properties and stability.
• High fluorescence intensity, brightness, and signal-to-noise ratios were achieved.
• Effective deep-tissue, three-dimensional imaging was demonstrated at an ultra-low two-photon excitation power level.
• The targeted AbEGFR antibody facilitated specific binding, enhancing imaging contrast.

Conclusions:

• N-GQD-PEI-PSS-AbEGFR serves as a highly effective two-photon contrast agent for bioimaging.
• The developed nanomaterial offers superior performance, including deep penetration and high signal, with minimal excitation power.
• This advancement holds significant potential for various biomedical imaging applications, particularly in deep-tissue visualization.