Creatinine-Detecting Laser Diode-Induced Fluorescence Detection System

Under highly alkaline conditions, creatinine reacts with 3.5-dinitrobenzoic acid (DNB) to produce a product that can absorb ultraviolet light at a wavelength of 400 nm and emit fluorescence at a wavelength of 491 nm. Thus, creatinine concentration can be calculated using fluorescence intensity. A novel fluorescence-based bioassay for rat creatinine that is capable of rapid detection at a low cost was developed in this study. A fluorescence sensing system was established using a micro-spectrometer, a 3-D translation stage, and a laser diode (LD) to measure various concentrations of serum creatinine. The measurable range was 12.5– $300 ~\mu $ mol/L ( ${R}^{2} $ = 0.996), and the limit of detection (LOD) was $5 ~\mu $ mol/L. The intraday precision and accuracy ranges were 7.33%–10.11% and 81.82%–99.75%, respectively, while the interday precision and accuracy ranges were 3.08%–9.39% and 86.75%–87.85%, respectively. Additionally, the test results for rat serum were compared with those from the National Laboratory Animal Center of National Applied Research Laboratories in Taiwan, and the correlation coefficient was determined to be 0.80.