Scientists at Hunan Normal University in China have made a significant breakthrough in fluorescence testing of trace blood components. While fluorescence tests are powerful in analyzing biomolecules, the strong autofluorescence of blood hampers accurate analysis. However, the research team has developed a novel fluorescence probe that effectively suppresses the interfering autofluorescence, enabling precise quantification of hydrogen sulfide (H2S), an important signal molecule.
Trace components in blood play a crucial role despite their low concentrations. For instance, H2S, a toxic gas known for its unpleasant odor of rotten eggs, serves as a vital messenger molecule in the body, involved in regulating circulation. Patients with cardiovascular diseases typically exhibit reduced H2S levels, while individuals with colon cancer often have elevated levels. Accurately quantifying these trace components is instrumental in diagnosis and investigating physiological and pathological relationships.
Fluorescence tests offer advantages in biomolecule analysis due to their affordability, simplicity, high sensitivity, and real-time measurement capabilities. Nonetheless, detecting trace components in whole blood samples poses challenges because the blood itself fluoresces strongly, overpowering weaker signals. Typically, the plasma is analyzed after centrifugation, but this compromises the accuracy of results by reducing unstable components and gas molecules.
To overcome these limitations, the research team, led by Hongwen Liu and Ronghua Yang, devised a novel fluorescence technique that enables the quantification of H2S in whole blood samples. The key lies in the fluorescence probe, which effectively quenches the interfering autofluorescence of blood. The fluorescence dye used is based on borodipyrromethene (BODIPY) modified with two molecular fragments that selectively “recognize” H2S. When H2S is present, the probe is activated, leading to fluorescence. Importantly, the autofluorescence of blood remains quenched, maintaining a low background fluorescence that does not interfere with the analysis.
The researchers successfully employed the new probe in fluorescence tests on whole blood samples from patients with cardiovascular diseases, confirming their reduced H2S levels. Similarly, tests on mice with colon cancer demonstrated the expected elevation in blood H2S concentrations.
Additionally, the team treated red blood cells from mice with allicin, the aromatic compound responsible for the medicinal properties of garlic, such as reducing blood pressure. Using their new probe, the researchers showcased that allicin triggers the formation of H2S in red blood cells.
This breakthrough opens up possibilities for the development of additional probes targeting other trace analytes in whole blood. The researchers are hopeful that this strategy will lead to further advancements in fluorescence testing, benefiting diagnosis and the exploration of physiological and pathological associations.