Second harmonic generating (SHG) nanoprobes for in vivo imaging

Area of Science:

• Biophysics
• Molecular Biology
• Nanotechnology

Background:

• Fluorescence microscopy is crucial for cell and molecular biology, enabling visualization of gene products.
• Fluorescent probes offer high contrast for single-molecule detection but face limitations like bleaching and saturation.
• Tissue autofluorescence can also impede imaging quality with traditional probes.

Purpose of the Study:

• To introduce and evaluate second harmonic generating (SHG) nanoprobes as an alternative to classical fluorescence probes for in vivo imaging.
• To demonstrate the advantages of SHG nanoprobes in overcoming common limitations of fluorescence imaging.

Main Methods:

• Utilized laser-scanning microscopy with intense illumination to excite SHG nanoprobes.
• Employed two-photon microscopy to detect the generated signal from SHG nanoprobes.
• Compared the performance of SHG nanoprobes against traditional fluorescent probes in imaging applications.

Main Results:

• SHG nanoprobes convert two photons into one photon of half the wavelength, appearing with an inverse Stokes shift.
• SHG nanoprobes exhibit superior stability, with no bleaching or blinking observed.
• The signal from SHG nanoprobes does not saturate under increasing illumination intensity, unlike fluorescent probes.
• SHG nanoprobes provide enhanced contrast and detectability for imaging.

Conclusions:

• SHG nanoprobes represent a significant advancement for in vivo molecular imaging.
• These nanoprobes circumvent key limitations of fluorescence probes, offering improved performance.
• SHG nanoprobes present unique advantages for imaging living cells and tissues with high fidelity.