Surface-Enhanced Raman Sensing: Glucose and Anthrax

This chapter outlines the use of surface-enhanced Raman spectroscopy (SERS) in the development of biological sensors for the detection of anthrax and glucose. In both cases, Ag film over nanosphere (AgFON) surfaces were used as the sensing platform. The localized surface plasmon resonance (LSPR) of AgFON surfaces was tuned to maximize the SERS signal for near infrar-red (NIR) excitations. A harmless analog of Bacillus anthracis, namely Bacillus sublilis, was quantitatively detected using SERS on AgFON surfaces. Calcium dipicolinate, an important biomarker for bacillus spores, was successfully measured with a limit of detection well below the anthrax infectious dose of 104 spores in I I minutes. For glucose detection, a mixed self-assembled monolayer (SAM) consisting of decanethiol (DT) and mercaptohexanol (MH) was immobilized on an AgFON surface to bring glucose within the zone of the localized electromagnetic field. Complete partitioning and departitioning of glucose was demonstrated. Furthermore, quantitative detection in vitro and in vivo was achieved.