Time-resolved fluorescence immunoassay for C-reactive protein using colloidal semiconducting nanoparticles.

Area of Science:

• Materials Science
• Nanotechnology
• Biochemistry

Background:

• Colloidal semiconductor nanoparticles (quantum dots) typically exhibit short-lived fluorescence (nanosecond decay times).
• A less-studied long-lived fluorescence component (microsecond decay times) exists in these nanomaterials when dispersed in buffer solutions.
• This long-lived emission has potential for advanced detection methods.

Purpose of the Study:

• To investigate and characterize the long-lived fluorescence component in colloidal semiconductor nanoparticles.
• To demonstrate the utility of this long-lived fluorescence for sensitive bioassays.
• To enhance signal-to-noise ratios in fluorescence detection.

Main Methods:

• Utilized cadmium telluride (CdTe) nanoparticles in phosphate-buffered saline (PBS) to study long-lived luminescence.
• Quantified the signal intensity increase of the microsecond-range fluorescence.
• Developed and demonstrated a time-resolved fluorescence immunoassay for C-reactive protein (CRP) detection using cadmium selenide-zinc sulfide (CdSe-ZnS) nanoparticles and green light excitation.

Main Results:

• Observed a significant 1,000-fold increase in the signal intensity of long-lived luminescence for CdTe nanoparticles in PBS.
• Established that long-lived fluorescence enables time-gated detection, improving signal-to-noise ratio.
• Successfully applied this principle in a time-resolved immunoassay for CRP detection.

Conclusions:

• Colloidal semiconductor nanoparticles possess a valuable long-lived fluorescence component.
• Time-gated detection utilizing microsecond-range fluorescence offers enhanced sensitivity and reduced background noise.
• This approach facilitates the detection of low concentrations of analytes, such as CRP, with improved accuracy.