Porous carbon nanowire array for highly sensitive, biocompatible, reproducible surface-enhanced Raman spectroscopy

Surface-enhanced Raman spectroscopy (SERS) is a powerful tool for vibrational spectroscopy as it provides several orders of magnitude higher sensitivity than inherently weak spontaneous Raman scattering by exciting localized surface plasmon resonance (LSPR) on metal substrates. However, SERS is not very reliable, especially for use in life sciences, since it sacrifices reproducibility and biocompatibility due to its strong dependence on "hot spots" and large photothermal heat generation. Here we report a metal-free (i.e., LSPR-free), topologically tailored nanostructure composed of porous carbon nanowires in an array as a SERS substrate that addresses the decades-old problem. Specifically, it offers not only high signal enhancement due to its strong broadband charge-transfer resonance, but also extraordinarily high reproducibility or substrate-to-substrate, spot-to-spot, sample-to-sample, and time-to-time consistency in SERS spectrum due to the absence of hot spots and high compatibility to biomolecules due to its fluorescence quenching and negligible denaturation capabilities. These excellent properties make SERS suitable for practical use in diverse biomedical applications.