Selective Visual Detection of TNT at the Sub-Zeptomole Level

摘要

Realizing the limits of sensitivity, while maintaining selectivity, is an ongoing quest. Among the multitude of requirements, national security, early detection of diseases, safety of public utilities, and radiation prevention are some of the areas in need of ultralow detection. Structural, functional, and electronic features of nanomaterials are used to develop reliable analytical methods. Several kinds of surface-enhanced spectroscopy, surface-enhanced Raman in particular, can be used for such applications; the technique may be further enhanced by spatially separating the analyte and the active plasmonic nanostructure with an insulator, a method known as shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS). Creating uniform anisotropic structures with nanoscale attributes by simple solution chemistry and combining analyte-selective chemistry on such surfaces enables ultrasensitive and selective detection methods. Noble metal quantum clusters (QCs), a new family of atomically precise nanomolecules with intense luminescence, along with their protein protected analogues, are highly sensitive and selective for specific analytes. Anchoring such QCs on mesoscale (100 nm to a few um) particles leads to surface-enhancement of their luminescence and can create a new platform for ultrasensitive detection, especially when combined with the use of optical microscopy. Gold meso-flowers (MFs) are anisotropic materials with unique five-fold symmetric stems containing surface-enhancing nanoscale features. An entire MF is only a few micrometers in size, and its distinct shape allows for unique identification by optical microscopy; thus, changes in the properties of an MF can be used for the immediate and efficient detection of analytes. Herein, we demonstrate the selective detection of 2,4,6-trinitrotoluene (TNT) at the sub-zeptomole level (10~(-21) moles) through a combination of these strategies on a mesostructure.