Rapid and scalable preparation of flexible Ag nanoparticle-decorated nanocellulose SERS sensors by magnetron sputtering for trace detection of toxic materials

Cellulose-based surface-enhanced Raman scattering (SERS) platforms have attracted extensive attention as a flexible, sustainable, eco-friendly and ultrasensitive sensor for trace detection of chemical and biological molecules. However, preparation of cellulose-based SERS substrates usually suffers from high cost, complicated fabrication step, time-consuming process and poor signal reproducibility. In this research, the flexible Ag nanoparticle-coated bacterial nanocellulose (AgNP@BNC) SERS substrates are successfully developed by a facile, low-cost, efficient and scalable magnetron sputtering technology. Taking advantage of the characteristics of magnetron sputtering technology, silver nanoparticles are rapidly and uniformly deposited onto the surface of BNC membrane. In addition, due to the large specific surface area, excellent permeability and adsorption properties of hydrophilic nanocellulose, the target molecules are also uniformly distributed on the surface of nanocellulose membrane. As a result, the optimal AgNP-120@BNC SERS substrate exhibits high sensitivity of 10^–9 M for crystal violet, remarkable signal homogeneity and excellent storage stability. The flexible AgNP-120@BNC SERS substrate also exhibits ultra-sensitive pesticide detection with a detection limit of 7.8 × 10^–8 M for lambda-cyhalothrin on irregular fruit surfaces by a feasible paste-and-read way. This research demonstrates promising application of magnetron sputtering technology in the development of flexible, low-cost and large-scale nanocellulose-based SERS sensors for trace detection of toxic materials. Graphical Abstract: [Figure not available: see fulltext.].