Early detection for carbohydrate antigen-19-9 based on surface enhanced Raman spectroscopy aptamer sensor

Background

Incipient screening for cervical cancer is crucial for treatment and improving prognosis. In this work, SERS based aptamer sensor (aptasensor) has been developed and applied to high-sensitivity detection of cervical cancer tumor marker (Carbohydrate antigen19-9 (CA19-9)) with a microporous chip, which was used as surface enhanced Raman scattering (SERS) analysis platform.

Methods

The aptamer of CA19-9 was immobilized on the gold nanodumbbell as a capture probe and the gold nanobipyramid containing complementary aptamer chains of the signal molecule Cy5 was modified as a signal probe. SERS aptasensor was constructed by combining signal probes and capture probes. It caused signal molecule Cy5 were sandwiched between the signal probes and capture probes; the constructed SERS aptasensor generated a strong SERS signal of Cy5. Based on the strong specificity of the aptamer, the CA19-9 aptamer binds specifically to CA19-9 when CA19-9 exist in the detection environment. The signal probe was released, resulting in a decrease in the SERS signal of the detection environment.

Results

Under the optimal detection conditions, the detection limit of the aptasensor was calculated to be 1.16 × 10⁻³ U/mL and limit of quantification is equal to 3.87 × 10⁻³ U/mL. In addition, a standard cervical cancer bearing mouse model was constructed and the SERS spectra of the serum of mice at different stages were measured. The CA19-9 content in the serum of mice at different stages was calculated. Compared with the results of enzyme-linked immunosorbent assay (ELISA), relative error (RE) values (2.54 %, −6.093 %, −4.922 %, and 3.04 %) of the CA19-9 concentrations detected by the two methods on the day of 0, 7, 14 and 28.

Conclusion

The proposed SERS aptasensor provides a new and reliable platform for early cervical cancer screening, and its low RE value proves that it will be a promising CA19-9 detection method.