Microfluidic-assisted synthesis of AuNPs/MoS2 substrate for surface-enhanced Raman scattering detection of adenine and cytosine in chicken

Surface-enhanced Raman scattering (SERS) is a powerful analytical tool capable acquisition of molecular fingerprint information in a rapid and non-destructive manner. Poor reproducibility of SERS rising from non-uniform substrates is a challenge impeding its abroad application. In this work, a microfluidic-assisted nanomaterials synthesis approach was applied for uniformly generation of Au nanoparticles (AuNPs) on molybdenum disulfide (MoS₂) nanoflowers, also named AuNPs/MoS₂ composites. The resulting AuNPs/MoS₂ composite exhibited excellent SERS activity. The enhancement factors of rhodamine 6G, methylene blue, adenine and cytosine using AuNPs/MoS₂ prepared in microchip were 17.1-fold, 11.5-fold, 5.7-fold and 4.2-fold larger than those prepared in flask, respectively. Moreover, the prepared AuNPs/MoS₂ composite shown great stability and good selectivity towards adenine and cytosine. Consequently, a SERS analytical method was established for adenine and cytosine analysis. The linear ranges were 15.2-1.11 × 10⁴ μg/L for adenine and 15.6-500 mg/L for cytosine, and detection limits were 4.3 μg/L for adenine and 5.0 mg/L for cytosine (S/N = 3). This SERS method was applied for adenine analysis in chicken heart and gizzard samples. The recovery rates for adenine ranged from 80.9% to 102%, with a relative standard deviation of less than 9.2%. The results were confirmed by HPLC method. The microfluidic-assisted nanomaterials preparation approach along with the SERS analytical method provided an efficient tool for complicated biosample analysis.