General\nSurface-Enhanced Raman Spectroscopy Method\nfor Actively Capturing Target Molecules in Small Gaps

Abstract

Over\nthe past decade, many efforts have been devoted to designing\nand fabricating substrates for surface-enhanced Raman spectroscopy\n(SERS) with abundant hot spots to improve the sensitivity of detection.\nHowever, there have been many difficulties involved in causing molecules\nto enter hot spots actively or effectively. Here, we report a general\nSERS method for actively capturing target molecules in small gaps\n(hot spots) by constructing a nanocapillary pumping model. The ubiquity\nof hot spots and the inevitability of molecules entering them lights\nup all the hot spots and makes them effective. This general method\ncan realize the highly sensitive detection of different types of molecules,\nincluding organic pollutants, drugs, poisons, toxins, pesticide residues,\ndyes, antibiotics, amino acids, antitumor drugs, explosives, and plasticizers.\nAdditionally, in the dynamic detection process, an efficient and stable\nsignal can be maintained for 1–2 min, which increases the practicality\nand operability of this method. Moreover, a dynamic detection process\nlike this corresponds to the processes of material transformation\nin some organisms, so the method can be used to monitor transformation\nprocesses such as the death of a single cell caused by photothermal\nstimulation. Our method provides a novel pathway for generating hot\nspots that actively attract target molecules, and it can achieve general\nultratrace detection of diverse substances and be applied to the study\nof cell behaviors in biological systems.