Utilizing ZnO mineralization for the synthesis of cellulose nanocomposites embedded with noble metal NPs for enhanced SERS detection

In this study, a cellulose composite material based on ZnO-Au nanoparticles was developed as a flexible and effective substrate for surface-enhanced Raman spectroscopy ( SERS) analysis. Through the biomineralization of cellulose, ZnO nanoflowers were formed inside it, and Au nanoparticles were well dispersed in the three-dimensional cellulose framework to prevent the uncontrolled aggregation of Au NPs. This resulted in abundant ‘hot spots’ for enhanced SERS signals. The morphology, structure and mechanical properties of the nanocomposites were further characterized. The nanocomposites exhibit excellent antibacterial activity and cell safety. Using rhodamine 6 G ( R6G) as a probe molecule, the substrate achieved a detection limit of 10⁻⁸ M and an enhancement factor ( EF) of 5.4 × 10⁷ with good reproducibility. In addition, due to the biocompatibility, porosity and mechanical flexibility of the SERS substrate, it can directly adsorb and detect pesticide residues in fruits and harmful dyes in traditional Chinese medicine, with detection limits of 0.1 ppm and 10⁻⁵ mg/ml, respectively. This environmentally friendly SERS substrate shows potential for food and drug safety applications.