Benzotriazole rhodamine B: effect of adsorption on surface-enhanced resonance Raman scattering

Polymer films developed for distance detection, containing dye-coated silver particles for ultra-sensitive analysis using surf ace-enhanced resonance Raman scattering (SERRS), identified the need for effective SERRS labels that interact strongly with the metal surfaces. Many dyes that are currently used for SERRS can be displaced from the surface owing to the relatively weak surface attachment, and therefore they do not adhere strongly enough to the surface for many practical applications, i.e. to withstand incorporation into environments such as paints, resins and polymers. Rhodamine dyes are very effective in SERRS under ideal laboratory conditions, as shown by the detection of single molecules. The synthesis of 19-[4-(benzotriazole-5-ylsulfamoyl)-2-methylphenyl]-6-diethylaminoxanthen-3-ylidene]diethylammonium (benzotriazole rhodamine B, BTRB), which was designed to give much stronger surface adhesion, was evaluated using SERRS in comparison with two commercially available rhodamine dyes, rhodamine 6G and rhodamine B. The increased strength of interaction with the roughened metal surface was shown to increase the versatility of BTRB in terms of the choice of aggregating agent and also the type of sample prepared. Therefore, the modification of rhodamine dyes to incorporate a benzotriazole group widens the range of practical applications for which they are suitable for detection using SERRS. Copyright (C) 2004 John Wiley Sons, Ltd.