A novel SERRS approach for the highly sensitive detection of bilirubin levels in urine

Bilirubin, as a major component of human bile and a byproduct of red blood cell metabolism, plays an essential role in diagnosing jaundice and assessing liver function. Surface-enhanced resonance Raman spectroscopy (SERRS) is a highly sensitive detection technique that emerged from the synergy of resonance Raman spectroscopy and surface-enhanced Raman spectroscopy (SERS). This technology not only provides molecular fingerprint information but also offers rapid detection, interference resistance, and high selectivity, making it particularly suitable for specific biological system detection. Herein, we have developed an innovative SERRS technique for efficiently measuring bilirubin levels in urine. This method involves precisely adjusting the pH of sodium nitrite to 1, oxidizing bilirubin to biliverdin. Subsequently, a portable Raman spectrometer with an excitation wavelength of 785 nm is used to emit its resonance Raman signal, achieving high-sensitivity and selective rapid detection. Through this approach, we have achieved the quantification of a wide linear dynamic range spanning from 860 nmol/L to 34.2 μmol/L, characterized by an excellent correlation coefficient of 0.99 and a remarkably low detection limit of 860 pmol/L, which is significantly below that of traditional detection methods. Moreover, in the analysis of real samples, minimal pre-treatment is required to achieve high sensitivity and expedited detection. The entire procedure is completed in merely 1 min, with recovery rates falling between 80 % and 100 %. This approach paves the way for the specific and rapid detection of biomarkers using Raman spectroscopy.