Up-conversion fluorescence "off-on" switch based on heterogeneous core-satellite assembly for thrombin detection.

Area of Science:

• Nanotechnology
• Biomedical Engineering
• Analytical Chemistry

Background:

• Upconversion (UC) nanoparticles (NaGdF4: Yb, Er) exhibit fluorescence properties.
• Thrombin detection is crucial for disease diagnosis.
• Existing detection methods may lack sensitivity or specificity.

Purpose of the Study:

• To develop a novel "off-on" fluorescence sensor for ultrasensitive thrombin detection.
• To utilize gold (Au) core and UC satellite nanoparticles for enhanced sensing capabilities.
• To validate the sensor's performance in detecting thrombin in human serum for diagnostic applications.

Main Methods:

• Fabrication of a fluorescence sensor using thrombin aptamer-modified Au core and complementary sequence-modified UC satellites.
• Optimization of assembly conditions to achieve high yield (80%) of Au core-UC satellites.
• Utilizing the fluorescence quenching and recovery mechanism upon thrombin binding for signal generation.

Main Results:

• The sensor demonstrated an "off-on" fluorescence switching mechanism.
• Achieved a high yield of Au core-UC satellite assembly.
• Exhibited high specificity for thrombin compared to other biomolecules.
• Reached an ultrasensitive limit of detection of 3.5 fg/mL.
• Showed satisfactory performance in detecting thrombin in human serum samples.

Conclusions:

• The developed Au core-UC satellite system provides an effective platform for ultrasensitive thrombin detection.
• The sensor's high specificity and sensitivity make it suitable for clinical diagnostics.
• This approach holds promise for early disease diagnosis through thrombin level monitoring in human serum.