posted on 2022-01-12, 19:09authored byBohan Yin, Willis Kwun Hei Ho, Qin Zhang, Chuanqi Li, Yingying Huang, Jiaxiang Yan, Hongrong Yang, Jianhua Hao, Siu Hong Dexter Wong, Mo Yang
Surface-enhanced
Raman scattering (SERS)-based biosensors are promising
tools for virus nucleic acid detection. However, it remains challenging
for SERS-based biosensors using a sandwiching strategy to detect long-chain
nucleic acids such as nucleocapsid (N) gene of severe acute respiratory
syndrome coronavirus 2 (SARS-CoV-2) because the extension of the coupling
distance (CD) between the two tethered metallic nanostructures weakens
electric field and SERS signals. Herein, we report a magnetic-responsive
substrate consisting of heteoronanostructures that controls the CD
for ultrasensitive and highly selective detection of the N gene of
SARS-CoV-2. Significantly, our findings show that this platform reversibly
shortens the CD and enhances SERS signals with a 10-fold increase
in the detection limit from 1 fM to 100 aM, compared to those without
magnetic modulation. The optical simulation that emulates the CD shortening
process confirms the CD-dependent electric field strength and further
supports the experimental results. Our study provides new insights
into designing a stimuli-responsive SERS-based platform with tunable
hot spots for long-chain nucleic acid detection.