Selective Q1 Q2 detection of non-aromatic pesticides via cyclodextrin-promoted fluorescence modulation† Dana J. DiScenza and Mindy Levine Q3 Reported herein is the detection of aliphatic pesticides using cyclodextrin-promoted fluorescence modulation. The introduction of the pesticide leads to noticeable changes in the emission of a fluorophore held in close proximity by cyclodextrin, leading to a pesticide detection system that operates with 100% successful differentiation and low limits of detection. Introduction The widespread use of pesticides is of significant concern due to the known and suspected toxicities of many small-molecule pesticides, 1 as well as their long-term environmental persistence. 2 Currently used methods for pesticide detection overwhelmingly rely on chromatography for the purification of the small molecule pesticides, followed by mass spectrometry for accurate pesticide identification. 3 Although such methods are highly sensitive for individual pesticides, they tend to suffer from tedious sample preparations, which limits the ability to conduct high throughput assays of multiple samples for multiple pesticide analytes. 4 Newer detection methods such as nanoparticle-based Raman spectro- scopy 5 and electrochemical assays 6 have recently been developed. The use of fluorescence-based methods for pesticide detection would be highly advantageous, as fluorescence spectroscopy is sensitive to even trace amounts of a target analyte, 7 can rapidly generate response signals, 8 and is amenable to the development of high throughput assays for rapid screening of multiple environ- mental samples. 9 Fluorescence assays for non-photophysically active compounds such as organochlorine pesticides (compounds 1–4, Fig. 1) are complicated by the fact that the analytes themselves do not have notable fluorescence signals, and require either derivatiza- tion 10 or an indirect method for efficient fluorescence detection. 11 Previous research in our laboratory led to the development of cyclodextrin-promoted energy transfer for the detection of aromatic toxicants and toxicant metabolites 12 in multiple complex environments. 13 This system uses the aromatic ana- lytes as energy donors in combination with high quantum yield fluorophore acceptors, which are held in close proximity by the supramolecular cyclodextrin scaffold. Recently, we have developed a new concept termed ‘‘fluores- cence modulation,’’ which enables the detection of aliphatic analytes that do not participate in cyclodextrin-promoted energy transfer. These analytes are detectable through quantifying proximity-induced changes in the fluorescence spectrum of a high quantum yield fluorophore upon introduction of the analyte (Fig. 2), with the cyclodextrin acting as a supramolecular scaffold 1 5 10 15 20 25 30 35 40 45 50 55 1 5 10 15 20 25 30 35 40 45 50 55 Cite this: DOI: 10.1039/c5nj02357b Fig. 1 Pesticides (1–4), control analyte 5, and fluorophores (6–8) under investigation. Fig. 2 Schematic illustration of cyclodextrin-promoted fluorescence modulation with several potential association complexes. Department of Chemistry, University of Rhode Island, 51 Lower College Road, Kingston, RI 02881, USA. E-mail: mlevine@chm.uri.edu; Fax: +1-401-874-5072; Tel: +1-401-874-4243 † Electronic supplementary information (ESI) available: Synthesis of fluorophore 6, experimental details for fluorescence modulation experiments, limit of detec- tion experiments, and fluorescence array experiments, summary tables and figures for all experiments. See DOI: 10.1039/c5nj02357b Received (in Montpellier, France) 3rd September 2015, Accepted 13th November 2015 DOI: 10.1039/c5nj02357b www.rsc.org/njc This journal is c The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2015 New J. Chem., 2015, 00,1 5| 1 NJC PAPER