Plasmonic SERS Substrates Based on Nanocellulose for Biomolecule Detection

In search of a higher life quality, the need to detect molecules in ultra-low concentrations has led to increasing efforts for identification and quantification. As such, Raman spectroscopy has gained attention, due to its selectivity and sensibility for identification of compounds, low sample preparation, high levels of detection and non-destructive analysis, have made it one of the pioneer techniques in identifying and analyzing biomolecules. These characteristics are increased through a technique called surface-enhanced Raman scattering (SERS), in which the increase in Raman signal can allow the detection of analytes at ultra-low concentrations, up to single-molecule, in complex samples. Hence, there is a surging need to design stable, uniform and reproducible SERS substrates, that exploit the scattered beams from the laser. In this context, cellulose-based plasmonic (AuNPs-based) substrates offer three-dimensional platforms, with high mechanical stability, which can enable an increased concentration of spots with an exceptional enhancement of the electromagnetic field (known as ‘hotspots’) through on-demand SERS using a collapsible mechanism of the cellulose substrate when the analyte is loaded. The presence of anisotropic gold structures, synthesized in a deep eutectic solvent (DES) through a one-pot synthesis, and immobilized by cellulose nanocrystals CNCs, follows current tendencies in green chemistry, which places them as an ideal alternative for the detection of a wide assortment of biomedical-interest analytes.