One-dimensional SERS nanoprobes based on cellulose nanocrystals and their biomaging performance

Surface enhanced Raman scattering spectroscopy (SERS) technology has received increasing attention in the bioimaging field. Herein, based on the support of cellulose nanocrystal (CNC) with thiol groups, one-dimensional (1D) "hot spot" structure was constructed by the self-assembly of gold nanoparticles (AuNPs) via Au -S bonding. Silica shell was subsequently coated on the CNC loaded with AuNPs to fabricate core-shell SERS nanoprobe, which was further successfully applied for the SERS imaging of Hela cells. Owing to the presence of silica shell, the nanoprobe exhibited excellent water-dispersible stability in phosphate buffer salt solution (PBS). Moreover, the silica shell effectively protected both the "hot spot" structure and the adsorbed Raman reporter of 4-mercaptobenzoic acid from external interference, thereby improving the signal stability of SERS nanoprobe. In addition, the plasma coupling of electromagnetic field between AuNPs and silica significantly enhanced the Raman signal of "hot spots". The SERS nanoprobe possessed good biocompatibility even at relatively high concentrations, and successfully achieved bioimaging of Hela cell using the Raman signal at 1580 cm -1 channel.