Ultrasensitive surface-enhanced Raman scattering detection in common fluids

• Published in: Proceedings of the National Academy of Sciences - PNAS 2016-01, Vol.113 (2), p.268-273
• Main Authors: Yang, Shikuan, Dai, Xianming, Stogin, Birgitt Boschitsch, Wong, Tak-Sing
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Biological Sciences; Environmental monitoring; Molecular biology; Molecular chemistry; Nanoparticles; Physical Sciences; Scattering; Spectrum analysis
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1518980113

Detecting target analytes with high specificity and sensitivity in any fluid is of fundamental importance to analytical science and technology. Surface-enhanced Raman scattering (SERS) has proven to be capable of detecting single molecules with high specificity, but achieving single-molecule sensitivity in any highly diluted solutions remains a challenge. Here we demonstrate a universal platform that allows for the enrichment and delivery of analytes into the SERS-sensitive sites in both aqueous and nonaqueous fluids, and its subsequent quantitative detection of Rhodamine 6G (R6G) down to ∼75 fM level (10−15 mol·L⁻¹). Our platform, termed slippery liquid-infused porous surface-enhanced Raman scattering (SLIPSERS), is based on a slippery, omniphobic substrate that enables the complete concentration of analytes and SERS substrates (e.g., Au nanoparticles) within an evaporating liquid droplet. Combining our SLIPSERS platform with a SERS mapping technique, we have systematically quantified the probability, p(c), of detecting R6G molecules at concentrations c ranging from 750 fM (p > 90%) down to 75 aM (10−18 mol·L⁻¹) levels (p ≤ 1.4%). The ability to detect analytes down to attomolar level is the lowest limit of detection for any SERS-based detection reported thus far. We have shown that analytes present in liquid, solid, or air phases can be extracted using a suitable liquid solvent and subsequently detected through SLIPSERS. Based on this platform, we have further demonstrated ultrasensitive detection of chemical and biological molecules as well as environmental contaminants within a broad range of common fluids for potential applications related to analytical chemistry, molecular diagnostics, environmental monitoring, and national security.