3D printed electrochemical sensor and microfluidic system for the detection of L-tryptophan using degradable material.

Herein, we constructed an integrated system for L-tryptophan (L-Trp) detection by assembling an electrochemical sensor and a microfluidic platform. Amongst, the sensor was printed using conductive polymer filaments and then chemically activated to expose porous nanostructure on the surface. A calibration curve was established between 31.26-1000.00 μmol/L and the limit of detection (LOD) was 10.41 μmol/L. The sensor exhibited satisfactory reproducibility, selectivity and stability. The recovery ranged between 99.06-102.09 % with relative standard deviations less than 5.21 %. The results show that L-Trp undergoes a two-proton, two-electron transfer in the anodic reaction. Once integrated into a printed microfluidic module from photosensitive resin, the sensor showed a wider detection range (15.00-70.00, 100-4000 μmol/L) with a lower LOD (5.00 μmol/L), which may be due to faster mass transfer in microfluidics. The consistency and validity were affirmed with ultra-visible spectrophotometer and HPLC. The integrated system allows point-of-testing owing to its small size, portability and low cost.