Ultrasensitive QRS made by supramolecular assembly of functionalized cyclodextrins and graphene for the detection of lung cancer VOC biomarkers† Sananda Nag, ab Lisday Duarte, c Emilie Bertrand, c V ´ eronique Celton, c Micka ¨ el Castro, a Veena Choudhary, b Philippe Guegan * de and Jean-François Feller * a A novel electronic nose system comprising functionalized b-cyclodextrin wrapped reduced graphene oxide (RGO) sensors with distinct ability of discrimination of a set of volatile organic compounds has been developed. Non-covalent modification of chemically functionalized cyclodextrin with RGO is carried out by using pyrene adamantane as a linker wherever necessary, in order to construct a supramolecular assembly. The chemical functionality on cyclodextrin is varied utilising the principle of selective chemical modification of cyclodextrin. In the present study, the combined benefits of the host–guest inclusion complex formation ability and tunable chemical functionality of cyclodextrin, as well as the high surface area and electrical conductivity of graphene, are utilized for the development of a set of highly selective quantum resistive chemical vapour sensors (QRS), which can be assembled in an electronic nose. 1. Introduction Enhancing the quality of life by decreasing the impact of severe diseases is still a global challenge. According to the World Health Organization (WHO), cancers which are killing each year 7.6 million people can be considered as a global priority. 1 The WHO has also projected that without immediate action, the global number of deaths from cancer will increase by nearly 80% by 2030, with most occurring in low- and middle-income countries. Cancers could be more efficiently treated in the case of an anticipated diagnosis, and from this point of view metabolomics can bring very promising solutions. This new and active eld of research is studying the volatile organic compounds (VOC) produced by a biological system to investi- gate the metabolite differences between natural and perturbed systems (cells, organs and tissues). Thus, metabolomics allows proling diseases such as cancer from a VOC ngerprint found in breath, urine, faeces, saliva, nasal mucus or gaseous excre- tions of the skin 2 or combinations of them. 3 Among these, exhaled breath is an excellent source containing several hundreds of VOC (including water) but at the ppm or ppb level, which makes their identication difficult. However, analyzing VOC proles with pattern recognition algorithms allows effi- cient discrimination between cancerous and healthy subjects. 4–13 Nevertheless, the commonly used techniques for breath VOC analysis such as GC-MS, 14 infrared spectroscopy, 15 ion ow tube mass spectrometry, 16 and optical spectroscopy 17 suffer from several shortcomings such as high cost, low-porta- bility, low sensitivity or high consumption. In contrast, arrays of nonspecic sensors, i.e., electronic noses (e-nose), have demonstrated their effectiveness in the detection of VOC. 18 E- noses present in particular the advantage of being non-invasive, cost effective, quick and portable. Additionally they allow real time monitoring 19 and provide almost directly a pattern of exhaled biomarkers in the form of a VOC breath print. 20 Moreover, a wide choice of vapour sensors can be assembled in the array, depending on the nature of the transducer: metal oxides (MO), 20,21 intrinsically conductive polymers (ICP), 22–24 and functionalized carbon nanomaterials or nanocomposites. 25–29 However, e-noses also have some drawbacks, such as processing and performance reproducibility, dri in the baseline and the response of sensors requiring sometimes recalibration. MO sensors oen have low sensitivity, a lack of selectivity, and a high operating temperature (several hundred degrees) imposed by their too high sensitivity to water, 30 whereas ICP sensors are too sensitive to humidity, irradiation and oxido-reduction. 31 a Smart Plastics Group, European University of Brittany (UEB), LIMAT B -UBS, Lorient 56321, France. E-mail: jean-francois.feller@univ-ubs.fr b Centre for Polymer Science & Engineering, Indian Institute of Technology, Delhi- 110016, India c Lab. of Analysis & Modelling for Biology & Environment (LAMBE-UMR 8587), University of Evry, 91025 Evry Cedex, France d Sorbonne Universit´ es, UPMC Univ. Paris 06, 75005 Paris Cedex, France. E-mail: philippe.guegan@upmc.fr e CNRS, UMR 8232, IPCM, Chimie des Polym` eres, 75005 Paris, France † Electronic supplementary information (ESI) available: Details of synthesis and characterization of functionalized cyclodextrins and reduced graphene oxide wrapped functionalized cyclodextrins. See DOI: 10.1039/c4tb01041h Cite this: J. Mater. Chem. B, 2014, 2, 6571 Received 27th June 2014 Accepted 28th July 2014 DOI: 10.1039/c4tb01041h www.rsc.org/MaterialsB This journal is © The Royal Society of Chemistry 2014 J. Mater. Chem. B, 2014, 2, 6571–6579 | 6571 Journal of Materials Chemistry B PAPER