Cellulose nanofibrils coated paper substrate to detect trace molecules using surface-enhanced Raman scattering

Acquisition of reproducible surface-enhanced Raman scattering (SERS) signals using paper-based SERS sensors is difficult because of the non-uniformity of the paper surface, which possesses a large number of pores and high surface roughness. To overcome the poor reproducibility of paper-based SERS sensors, they were coated with cellulose nanofibrils (CNF) obtained from pulp fibers, which fill the pores and decrease the local height differences on the paper's surface. The combination of hydrophobic modification and the improved uniformity and smoothness of the surface after CNF coating increased the coverage of silver nanoparticles (AgNPs) in the SERS spots from 87 to 95% and gave a more uniform distribution of the AgNPs on the SERS substrate. When a high magnification lens was used for sensitive molecular detection, the hydrophobic CNF-coated paper-based SERS sensor reduced the relative standard deviation of the SERS intensity and improved the limit of detection for rhodamine 6G. The CNF coating on paper was found to afford a more effective and reproducible paper-based SERS sensor than conventional filter paper. [GRAPHICS] .