Low temperature-promoted surface plasmon resonance effect and ultrasensitive surface-enhanced Raman scattering detection of creatinine

Creatinine is a key biomarker for the diagnosis and monitoring of kidney disease, so rapid and sensitive testing is very important. Raman spectroscopy is particularly suitable for the quantitative detection of creatinine in the human environment because it is sensitive to subtle changes in the concentration of the analyte. This paper provides an effective strategy to promote the activity of surface-enhanced Raman scattering spectroscopy by enhancing the photon-induced charge transfer efficiency at low temperature. The nano-gold icosahedron (Au₂₀) was obtained by the seed-growing method, which was used as the active substrate for SERS. The ultra-low temperature (98 K) SERS detection technology was used to realize the rapid and sensitive detection of the dye molecule crystal violet (CV) and creatinine in normal saline. The experimental results show that:at the room temperature of 296 K, the detection limit of Au₂₀ substrate for CV molecules was as low as 10^-12 M, and the signals were uniform; at the low temperature of 98 K, the detection limit of CV molecules can reach 10^-14 M, which is two orders of magnitude lower than that at 296 K. As a result, the adopted cryogenic temperature can effectively weaken the lattice thermal vibration and decrease the release of phonons, then suppress phonon-assisted non-radiative recombination. So, it will increase the number of photo-induced electrons to participate in the photo-induced charge transfer efficiency. Finally, we performed label-free detection of creatinine in saline using an Au₂₀ substrate. The results showed that the detection limit of the SERS substrate for creatinine was 10^-6 M at room temperature of 296 K, and the linear correlation coefficient of the 1619 cm^-1 peak was 0.9839. At the low temperature of 98 K, the detection limit of creatinine concentration was as low as 10^-8 M, and the linear correlation coefficient of the 1619 cm^-1 peak became 0.9973. It can be seen that low temperature may further improve the detection limit of creatinine concentration and the linearity of characteristic peak. In summary, the current work provides a new idea for the accurate detection of creatinine concentration in the field of biomedicine.