Sensors and Actuators B 166–167 (2012) 467–472 Contents lists available at SciVerse ScienceDirect Sensors and Actuators B: Chemical journa l h o mepage: www.elsevier.com/locate/snb Surface decoration of ZnO nanoparticles: A new strategy to fine tune the recognition properties of imine linked receptor Hemant Sharma a , Navneet Kaur b , Thangarasu Pandiyan c,∗ , Narinder Singh a,∗ a Department of Chemistry, Indian Institute of Technology Ropar, Rupnagar, Panjab 140001, India b Centre for Nanoscience & Nanotechnology, Panjab University, Chandigarh, Panjab 160014, India c Faculty of Chemistry, National Autonomous University of Mexico (UNAM), Mexico a r t i c l e i n f o Article history: Received 25 October 2011 Received in revised form 16 January 2012 Accepted 21 January 2012 Available online 10 March 2012 Keywords: Chemosensor Quantum dot Nanoparticles ZnO a b s t r a c t A dipodal receptor bearing imine linkages is decorated on the surface of ZnO nano-particles. The cation recognition properties of pure dipodal receptor are compared with the assembly having same recep- tor decorated on ZnO. The remarkable changes in the recognition profile are established and the ZnO coated with dipodal receptor system authenticates its use as a sensitive and selective sensor for Mg 2+ in semi-aqueous medium. The ZnO coated dipodal receptor can be used to recognize the Mg 2+ in cells of Saccharomyces cerevisiae. © 2012 Elsevier B.V. All rights reserved. 1. Introduction The development of chemosensors for the identification and quantification of important physiological and environmental ana- lytes are of considerable importance [1–7]. The search is focused for the high sensitivity, selectivity and multifunctionality of these chemosensors for their effective operational usage [8–10]. Some- time, selective chemosensors require long synthetic skills for the formulation of a receptor pseudocavity compatible with analyte [11,12]. Moreover, receptor pseudocavity must be unique for the analyte of interest and should not offer coordination sites for other types of analytes, not even for closely related i.e., selectivity for one metal ion among other metal ions etc. Earlier, it is shown that the decoration of a non-selective receptor on the surface of CdSe/ZnS (QDs) results in a nanocrystal hybrid, which has unique selectivity for two metal ions only through changes in UV-Vis Spectrum [13]. This unique selectivity authenticates the use of this receptor sys- tem for the simultaneous estimation of two metal ions. The theme of this strategy is based upon the idea that a free organic recep- tor is expected to be highly flexible and may adopt any geometry according to the steric requirement of any metal ion. However, if ∗ Corresponding authors. Tel.: +91 1881242176/+52 55 5622 3499; fax: +91 1881223395. E-mail addresses: pandiyan@unam.mx (T. Pandiyan), nsingh@iitrpr.ac.in (N. Singh). flexibility of this receptor is retarded, then this may improve the selectivity of the receptor. Under this strategy, the decoration of organic receptor on the surface of nanoparticle may restrict some of the coordination modes; this will result into a relatively more selective sensor [13]. The use of quantum dot as signaling unit is well documented in literature [14–18]; only few reports are avail- able where the QDs are used as platform to anchor the organic ligands. Zinc oxide (ZnO) is a wide band gap semiconductor, having high exciton binding energy of 60 meV and has stable wurtzite structure [19,20]. It has attracted intensive research efforts for its unique properties and versatile applications in antireflec- tion coatings, transparent electrodes in solar cells, ultraviolet (UV) light emitters, diode lasers, piezoelectric devices, spin- electronics, surface acoustic wave propagator, antibacterial agent, photonic material and for sensing application [21]. In spite of these diverse applications, the use of ZnO as a platform to organize non-selective receptor binding to an assembly, selec- tive for particular analyte is not explored. Although, similar to CdSe/ZnS (QDs) [13], the relatively cheaper ZnO decorated with non-selective receptor may results into a nanocrystal hybrid, with unique selectivity for particular metal ion. Thus in continua- tion to the research interest of our research group [22–27], the present investigation is designed to explore the possibility to dec- orate the imine linkaged dipodal receptor on the surface of ZnO nanoparticles to fine tune the recognition properties of resultant sensor. 0925-4005/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.snb.2012.01.076