In-situ growth of silver nanoparticles on 3D cellulose nanofibrous network for SERS sensing of pesticide residues on uneven surfaces

In this work, 3D nanofibrous network of bacterial nanocellulose (BNC) was employed as matrix template material in a composite system. The plasmonic silver nanoparticles (AgNPs) were in-situ grown onto the nanofibrous network of BNC to form AgNPs@BNC composite nanofibers. Flexible 3D SERS substrates of BNC nanofibrous network with various AgNPs loadings were manufactured by a simple and rapid vacuum-filtration route. Silver nanoparticles were uniformly and firmly embedded into nanocellulose supporting substrate to form 3D high-density SERS hot spots, resulting in a significant enhancement of electromagnetic field. In addition, the hydrophilic BNC demonstrates exceptional adsorption and permeation characteristics, allowing for the capture of target molecules in hotspot regions to amplify detection sensitivity. Consequently, the AgNPs decorated BNC SERS substrate achieves a notable detection sensitivity of 10⁻¹⁴ M, prominent signal homogeneity (RSD=7.3 %) and remarkable storage stability (over a month) for malachite green molecules. A lowest distinguishable level of 10⁻⁹ M for carbendazim molecules is also achieved. Moreover, carbendazim residues on uneven fruit surfaces can be directly and rapidly recognized by flexible AgNPs@BNC SERS sensor using a facile adhere-and-read method.