SERS-based biosensor with Raman-active external responsive element for rapid determination of adenosine monophosphate

Phosphorylated adenosine derivatives are important biological molecules with diverse biological functions connected with the energetic balance of the cell, biosynthesis of cell components and regulation of protein activity. Measurement of these compounds provides information about the cell signalling in the body as well as the quantity of microorganisms in the environment. Surface-enhanced Raman spectroscopy (SERS) is an optical method that provides a unique spectrum of a substance at low concentrations. Specificity and limit of detection of SERS-based sensors can be increased drastically using nucleic acid aptamers and Raman-active dyes, respectively. Here we describe an adenosine monophosphate (AMP) biosensor based on AMP-dependent interaction between the well-known DNA aptamer for AMP and a novel Raman-active dye. The SERS intensity of novel Black Hole Quencher-2 (BHQ-2) derivatives was shown to be proportional to the charge of the molecule indicating electrostatic interactions with negatively charged colloidal silver nanoparticles. The novel derivative of BHQ-2 with two amine groups, BHQ-2-(NH