Functionalized MoS.sub.2: circular economy SERS substrate for label-free detection of bilirubin in clinical diagnosis

A one-pot hydrothermal synthesis of Fe-doped MoS.sub.2 nanoflowers (Fe-MoS.sub.2 NFs) has been developed as a surface-enhanced Raman spectroscopy (SERS) substrate. The Fe-MoS.sub.2 NFs display high reproducibility, stability, and recyclability, which is beneficial for the development of the sustainable ecological environment. The SERS substrate provides a high enhancement factor of 10.sup.5, which can be ascribed to the inducing defects by doping Fe that can improve the charge transfer between probe molecules and MoS.sub.2. The Fe-MoS.sub.2 NFs have been used to detect bilirubin in serum. The Fe-MoS.sub.2 NF SERS substrate exhibits a linear detection range from 10.sup.-3 to 10.sup.-9 M with a low limit of detection (LOD) of 10.sup.-8 M. The substrate displays an excellent selectivity to bilirubin in the presence of other potentially interfering molecules (dextrose and phosphate). These results provide a novel concept to synthesize ultra-sensitive SERS substrates and open up a wide range of possibilities for new applications of MoS.sub.2 in clinical diagnosis. Graphical