A gold@silica core–shell nanoparticle-based surface-enhanced Raman scattering biosensor for label-free glucose detection

•We successfully synthesized Au nanstar@SiO2 NPs conjugated with the GOx enzyme.•We quantitatively measured glucose level by examining SERS peak of H2O2.•SERS sensing assay showed good anti-interference capability against UA and AA.•This sensor can be used in the real biological matrix such as saliva. The gold nanostar@silica core–shell nanoparticles conjugated with glucose oxidase (GOx) enzyme molecules have been developed as the surface-enhanced Raman scattering (SERS) biosensor for label-free detection of glucose. The surface-immobilized GOx enzyme catalyzes the oxidation of glucose, producing hydrogen peroxide. Under laser excitation, the produced H2O2 molecules near the Au nanostar@silica nanoparticles generate a strong SERS signal, which is used to measure the glucose concentration. The SERS signal of nanostar@silica∼GOx nanoparticle-based sensing assay shows the dynamic response to the glucose concentration range from 25μM to 25mM in the aqueous solution with the limit of detection of 16μM. The sensing assay does not show any interference when glucose co-exists with both ascorbic acid and uric acid. The sensor can be applied to a saliva sample.