Au nanoparticles functionalized 3D-MoS₂ nanoflower: An efficient SERS matrix for biomolecule sensing

Fabrication of Molybdenum disulfide (MoS₂) nanostructures and surface functionalization with noble metal nano particles is an emerging field of research as it has potential applications in electronic devices and chemical sensing. Here we report application of gold nanoparticles (AuNPs) decorated MoS₂ nanoflowers (Au-MoS₂ NFs) as an efficient bio-sensor. MoS₂ NFs, synthesized using green synthesis process, are further functionalized with AuNPs to tune their physical properties and make them more appropriate for biological applications. The abundant 'hot-spots' created by AuNPs through localization of electromagnetic field endows the Au-MoS₂ hybrid structure as an excellent substrate for biochemical sensing through surface enhanced Raman scattering (SERS). The sensing efficiency of the SERS substrate is examined using Rh6G as probe molecule with concentration as low as 10^-12 M. Main emphasis is given in detecting free bilirubin, an important component of human blood, using SERS technique. Au-MoS₂ NF SERS substrate exhibits high sensitivity, stability and excellent reproducibility in sensing bilirubin from high level (10^-3 M) to picomolar level. The concentration (C) dependent SERS intensity (I) is found to follow the general relationship I = C^α, with α ranging from 0.09 to 0.12. The substrate shows excellent selectivity and reliability while sensing of free bilirubin performed in human serum in the presence of crucial interferences such as dextrose, cholesterol and phosphate. In the present study, this Au-MoS₂ hybrid offers a new potential biosensing technology for free bilirubin detection and is anticipated to be applied for clinic diagnosis.