Enhanced fluorescence from semiconductor quantum dot-labelled cells excited at 280 nm

Area of Science:

• Biophotonics and Imaging
• Materials Science
• Cell Biology

Background:

• Semiconductor quantum dots (QDs) offer superior photostability and quantum yield over traditional fluorophores for microscopy.
• Current limitations in light sources and optics often necessitate exciting QDs far from their optimal deep-ultraviolet (deep-UV) wavelengths.
• Excitation at suboptimal wavelengths can reduce fluorescence intensity and image quality in cellular imaging applications.

Purpose of the Study:

• To quantitatively compare the excitation efficiency of semiconductor quantum dots (QDs) at 280 nm versus 365 nm within a cellular environment.
• To evaluate the impact of deep-UV excitation on fluorescence intensity, image quality, and photobleaching of QDs.
• To assess the cellular tolerance to high-intensity 280 nm irradiation for extended imaging periods.

Main Methods:

• Comparative quantitative analysis of semiconductor QD excitation at 280 nm and 365 nm in cellular samples.
• Measurement of fluorescence intensity and assessment of image quality across multiple datasets.
• Evaluation of QD photobleaching under 280 nm excitation and assessment of cellular viability/tolerance during prolonged irradiation.

Main Results:

• Excitation at 280 nm resulted in significantly increased fluorescence intensity, with an average increase of up to 3.59-fold compared to 365 nm excitation.
• Enhanced image quality was observed with 280 nm excitation, indicating improved signal-to-noise ratio and detail visualization.
• No significant photobleaching of QDs was detected at 280 nm, and approximately 80% of cells tolerated high-intensity irradiation over 6 hours.

Conclusions:

• Deep-UV excitation at 280 nm is a highly effective method for enhancing semiconductor QD performance in cell imaging.
• This approach overcomes limitations of traditional excitation wavelengths, offering superior fluorescence intensity and image quality without compromising QD stability.
• The demonstrated cellular tolerance supports the feasibility of using 280 nm excitation for advanced, long-term live-cell imaging applications with semiconductor QDs.