Photochemical functionalisation of optical nanotips with a rhodamine chemosensor for remote through-fiber detection of Hg2+

Abstract

For remote Hg²⁺ detection, an array of nanotips was covalently functionalised using a versatile photochemical approach. After chemical etching of an optical fiber bundle to generate the nanotip array, a protected n-propyl amine was grafted onto the tip surface by silanisation and thereafter photodeprotected by irradiation at 365 nm. The new rhodamine-based probe 9 developed for detection of Hg²⁺ was linked to the liberated amino group using the HOBt/DCC protocol. The optical fiber bundles functionalised with 9 exhibited a high selectivity toward Hg²⁺in situ, in full analogy to its precursor 4 in solution. Titration of the functionalised optical fiber bundles using a remote detection mode showed a detection range from 10⁻⁵ to 5 × 10⁻³ M for mercury ions in aqueous medium.