Journal
NANO LETTERS
Volume 13, Issue 11, Pages 5039-5045Publisher
AMER CHEMICAL SOC
DOI: 10.1021/nl401920u
Keywords
Wide-range SERS; reproducibility; biomolecule detections; multiplex detections; nanowires array
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Funding
- Research Grants Council of the Hong Kong Special Administrative Region, China [CityU 101909]
- National Basic Research Program of China (973 program) [2012CB932400]
- Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)
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Surface-enhanced Raman scattering (SERS) systems utilizing the interparticle nanogaps as hot spots have demonstrated ultrasensitive single-molecule detection with excellent selectivity yet the electric fields are too confined in the small nanogaps to enable reproducible biomolecule detections. Here, guided by finite-difference-time-domain simulation, we report hexagonal-packed silver-coated silicon nanowire (Ag/SiNW) arrays as a nanogap-free SERS system with wide-range electric fields and controlled interwire separation. Significantly, the system achieves a SERS detection of long double-strand DNA of 25-750 nm in length with a relative standard deviation (RSD) of 14% for measurements of above 4000 spots over an area of 200 x 200 mu m(2). The high reproducibility in the SERS detection is attributed to (1) the large interwire spacing of 150 nm that allows access and excitation of large biomolecules; and (2) 600 nm wide-range electric field generated by propagating surface plasmons along the surface of continuous Ag coating on a SiNVV. Moreover, a reproducible multiplex SERS measurement is also demonstrated with RSDs of 7-16% with an enhancement factor of similar to 10(6). The above results show that the ordered Ag/SiNW array system may serve as an excellent SERS platform for practical chemical and biological detection.
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