Abstract:
Large scale hotspot engineering is a significant approach for the development of highly efficient sur face enhanced Raman scattering (SERS) platforms. Herein, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-
oxidized nanocellulose fiber (T-NCF) serves as a labyrinth for developing highly sensitive and stable silver based SERS platform enabling single molecular level SERS detection of analytes. The SERS activity of 4-
methylbenzenethiol (4-MBT) in silver nanoconstructs with dissimilar size and shape (denoted as Ag/NCF-I
and Ag/NCF-II systems) synthesized by varying T-NCF to Ag+ ratio, exhibited femtomolar sensitivity re gardless of their structural variation. A detailed investigation of the SERS performance of both systems
with 4-MBT at extremely low concentration (10−15 M) is carried out with the help of large-area Raman
intensity mapping in order to evaluate the role of T-NCF in Raman signal enhancement. The analytical
enhancement factors (AEFs) for Ag/NCF-I and Ag/NCF-II are calculated to be 1.4 × 1012 and 4.8 × 1011,
respectively. A mechanism of local enrichment of analytes is postulated anticipating the ability of flexible
nanocellulose fibers to congregate AgNPs, resulting in induced plasmonic coupling of local electromag netic fields and high-intensity hotspot generation. The potential of T-NCF in generating hotspots can be
considered as an alternative strategy to develop standards with long-term colloidal stability and scale-up
production of highly sensitive AgNP based plasmonic platforms. This investigation ascertains the poten tial of nanocellulose fibers in the development of a robust lithography-free SERS sensing platform with
single molecule level sensitivity
