CdSe/CdS semiconductor quantum rods as robust fluorescent probes for paraffin-embedded tissue imaging

Area of Science:

• Biomedical Imaging
• Nanotechnology
• Histology

Background:

• Immunofluorescence is crucial for analyzing tissue markers and cell fate but is hindered by autofluorescence in formalin-fixed paraffin-embedded (FFPE) tissues.
• Existing imaging probes often struggle with background noise, limiting their effectiveness in FFPE samples.

Purpose of the Study:

• To evaluate the efficacy of rod-like semiconductor nanocrystals (QRs) as fluorescent probes in FFPE tissue sections.
• To compare the performance of QRs against conventional quantum dots (QDs) for in vivo cell tracking and tissue analysis.

Main Methods:

• Intramuscular injection of QRs and CdSe/ZnS quantum dots (QDs) into living mice.
• Confocal microscopy analysis of formalin-fixed paraffin-embedded muscle tissue sections at various time points post-injection.

Main Results:

• Rod-like QRs were clearly detectable in FFPE muscle sections 24 hours after injection, even at low picomole quantities.
• QR fluorescence signal intensity was significantly stronger than that of similarly functionalized QDs.
• QR fluorescence persisted for over 21 days post-injection, demonstrating long-term stability.

Conclusions:

• Rod-like semiconductor nanocrystals (QRs) provide a robust and sensitive alternative to traditional quantum dots for fluorescence imaging in FFPE tissues.
• QRs effectively overcome the autofluorescence limitations of FFPE samples, enabling clearer visualization of injected cells and tissue markers.
• The prolonged signal stability of QRs makes them highly suitable for long-term in vivo tracking studies.