Spatial deformation of nanocellulose hydrogel enhances SERS

Bacterial cellulose hydrogels containing gold nanoparticles (AuNPs-BC) were prepared using a cost-effective and environment-friendly in situ synthesis method. Well-dispersed AuNPs were grown on the nanofiber surface of the BC hydrogel, forming substrates of surface-enhanced Raman spectroscopy (SERS). Increases in SERS-active sites in the AuNPs-BC hydrogel caused the enhancement of SERS intensity. The enhancement in SERS intensity of 4-fluorobenzenethiol and phenylacetic acid (PAA), used as test analytes, was compared with spatially-un-deformed AuNPs-BC hydrogels, as well as spatially-deformed AuNPs-BC hydrogels in which the BC layers had contracted during drying. Particularly noteworthy was the detection of PAA by the simple contraction of the substrate, despite a low affinity to surface gold.