Synthesis of a nanogap-rich three-dimensional plasmonic AuNP film for label-free detection of multiple enzymes.

We synthesize a three-dimensional (3D) plasmonic AuNP film and further construct a SERS platform for label-free detection of multiple enzymes. The integration of a plasmonic AuNP film with ultrasmall nanogaps can generate a strong electromagnetic field and an amplified near-field enhancement effect with an enhancement factor (EF) of 5.9 × 106. This SERS platform can sensitively measure multiple enzymes without the involvement of either chemical labeling or separation.