http://mdpi.com/journal/sensors/special_issues/supramolecular_sensors/ Supramolecular chemistry is a comparatively young branch of the science that began to emerge as a distinct discipline in the late 1960s. Although work on complex molecular systems can be traced back to the early 19th Century, the term 'supramolecular chemistry' was only introduced in 1987 by the Nobel Prize winning chemist Jean-Marie Lehn. He defined it as the "chemistry of molecular assemblies and of the intermolecular bond" or, more simply, "chemistry beyond the molecule". Given this definition, almost all of chemistry and biology could be thought of as 'supramolecular' - from the crystallisation of sodium chloride to viral infection - but, crucially, supramolecular researchers use their knowledge of intermolecular interactions to manipulate molecular recognition events. Sensing applications of supramolecular chemistry, in which molecules are chosen for their size, shape and charge complementarity with the desired analyte, rely on exploiting the forces involved in the formation of non-covalent 'host-guest' complexes. The 'host' molecules, containing a binding site that is highly specific for an analyte 'guest', are used as sensors to register analyte binding through a variety of mechanisms such as colorimetric, fluorescent or electrochemical signals. The most significant non-covalent factors are electrostatics, cation-? interactions, hydrogen bonding, ?-? stacking and van der Waals forces. Although often individually weak, these intermolecular interactions exert a great influence on the stability of supramolecular complexes through a synergistic effect. The application of a 'supramolecular philosophy' to problems in analytical science has led to a range of molecules capable of recognising analytes with high specificity. In all cases the requirements of the sensor are the same: the host must bind to the guest in preference to all competing species and it must register the binding event in a measureable form. This has led to the 'receptor-spacer-reporter' design of many supramolecular sensors. This issue of Sensors illustrates the range of compounds that can be incorporated into sensors to help detect and monitor analytes of environmental and medical importance. Supramolecular chemistry is central to such research as it stands at a point where the spheres of chemistry, biology and diagnostic techniques intersect. http://mdpi.com/1424-8220/8/6/3689/ This paper presents the synthesis, the structural determination and the sensing capabilities toward Volatile Organic Compounds (VOCs) of a new class of fluorescent indolizine-cyclodextrin sensors. Two different pathways, both involving bipyridinium ylides and 6-amino-b-cyclodextrin, have been used to carry out the synthesis of these sensors. The macrocycle structures were dominantly established by 1H-NMR spectra and systematically studied by molecular modelling (MM3, AM1, AM1-COSMO methods). The sensing capabilities of the sensors were evaluated by emission of fluorescence, during the inclusion of the guest (adamantanol or aromatic derivatives) into the cyclodextrin (CD) host cavity. The host/guest complex formation was investigated by formation constant determinations, using experimental methods, coupled with theoretical calculations of formation energies using a specific docking procedure. Both experimental and theoretical results suggest that some compounds would make very attractive sensors for VOC detection. Some compounds could also be taken into consideration as biological markers. http://mdpi.com/1424-8220/8/6/3689/ Mon, 02 Jun 2008 00:00:00 CEST Sensors 2008-06-02 8 6 Article 3689 3705 1424-8220 Fluorescent Indolizine-b-Cyclodextrin Derivatives for the Detection of Volatile Organic Compounds 2008-06-02 doi: 10.3390/s8063689 Matthieu Becuwe David Landy François Delattre Francine Cazier Sophie Fourmentin http://mdpi.com/1424-8220/8/3/1645/ Ionophore incorporated PVC membrane sensors are well-established analyticaltools routinely used for the selective and direct measurement of a wide variety of differentions in complex biological and environmental samples. Potentiometric sensors have someoutstanding advantages including simple design and operation, wide linear dynamic range,relatively fast response and rational selectivity. The vital component of such plasticizedPVC members is the ionophore involved, defining the selectivity of the electrodes' complexformation. Molecular recognition causes the formation of many different supramolecules.Different types of supramolecules, like calixarenes, cyclodextrins and podands, have beenused as a sensing material in the construction of ion selective sensors. Schiff's bases andcrown ethers, which feature prominently in supramolecular chemistry, can be used assensing materials in the construction of potentiometric ion selective electrodes. Up to now,more than 200 potentiometric membrane sensors for cations and anions based on Schiff'sbases and crown ethers have been reported. In this review cation binding and anioncomplexes will be described. Liquid membrane sensors based on Schiff's bases and crownethers will then be discussed. http://mdpi.com/1424-8220/8/3/1645/ Tue, 11 Mar 2008 00:00:00 CET Sensors 2008-03-11 8 3 Article 1645 1703 1424-8220 Schiff's Bases and Crown Ethers as Supramolecular Sensing Materials in the Construction of Potentiometric Membrane Sensors 2008-03-11 doi: 10.3390/s8031645 Farnoush Faridbod Mohammad Reza Ganjali Rassoul Dinarvand Parviz Norouzi Siavash Riahi http://mdpi.com/1424-8220/7/12/3166/ A reversible photo-driven sensor for aluminum ions based on photochromicspiropyran was reported with rapid response time. The detection of aluminum wasperformed via the chelation of aluminum ions with the merocyanine form (MC) ofphotochromic spiropyran. 1H NMR studies confirmed the conversation from the MC forminto the Al3+ -MC form. Addition of aluminum ions to the spiropyran (SP) in a MeCN/H2Omixture results in obvious color changes with a loss in absorbance at 539 nm and anenhancement in absorbance at about 420 nm after irradiation at 365 nm. The metal chelationcomplex (Al3+ -MC) can also be converted into the original SP form by irradiation withvisible light. Aluminum ions can be detected down to 0.5 μM levels in a fast response ofless than 5 seconds with no interference from other ionic species. http://mdpi.com/1424-8220/7/12/3166/ Thu, 06 Dec 2007 00:00:00 CET Sensors 2007-12-06 7 12 Article 3166 3178 1424-8220 Thermally Stable Merocyanine Form of Photochromic Spiropyran with Aluminum Ion as a Reversible Photo-driven Sensor in Aqueous Solution 2007-12-06 doi: 10.3390/s7123166 Jiaqiang Ren He Tian http://mdpi.com/1424-8220/7/10/2096/ The synthesis of new fluorescent probes containing the thiophene andbenzoxazole moieties combined with an alanine residue is described. The resulting highlyfluorescent heterocyclic alanine derivatives respond via a quenching effect, withparamagnetic Cu(II) and Ni(II) metal ions and with diamagnetic Hg(II), as shown by theabsorption and steady-state fluorescence spectroscopy studies. The formation ofmononuclear or dinuclear metal complexes was postulated based on the presence of thefree carboxylic acid as binding site and also with the interaction with the donor atoms inthe chromophore. Interaction with other important biological metal ions such as Zn(II),Ca(II) and Na(I) was also explored. http://mdpi.com/1424-8220/7/10/2096/ Wed, 03 Oct 2007 00:00:00 CEST Sensors 2007-10-03 7 10 Article 2096 2114 1424-8220 Synthesis, Characterization and Metal Ion Detection of Novel Fluoroionophores Based on Heterocyclic Substituted Alanines 2007-10-03 doi: 10.3390/s7102096 Susana P. G. Costa Elisabete Oliveira Carlos Lodeiro M. Manuela M Raposo http://mdpi.com/1424-8220/7/9/1731/ Fluorescent self assembled monolayers (SAMs) on glass were previouslydeveloped in our group as new sensing materials for metal ions. These fluorescent SAMs arecomprised by fluorophores and small molecules sequentially deposited on a monolayer onglass. The preorganization provided by the surface avoids the need for complex receptordesign, allowing for a combinatorial approach to sensing systems based on small molecules.Now we show the fabrication of an effective microarray for the screening of metal ions andthe properties of the sensing SAMs. A collection of fluorescent sensing SAMs wasgenerated by combinatorial methods and immobilized on the glass surfaces of a custom-made 140 well microtiter-plate. The resulting libraries are easily measured and show variedresponses to a series cations such as Cu2+ , Co2+ , Pb2+ , Ca2+ and Zn2+ . These surfaces are notdesigned to complex selectively a unique analyte but rather they are intended to producefingerprint type responses to a range of analytes by less specific interactions. The unselectiveresponses of the library to the presence of different cations generate a characteristic patternfor each analyte, a “finger print” response. http://mdpi.com/1424-8220/7/9/1731/ Wed, 05 Sep 2007 00:00:00 CEST Sensors 2007-09-05 7 9 Article 1731 1746 1424-8220 Cross-Reactive Sensor Array for Metal Ion Sensing Based on Fluorescent SAMs 2007-09-05 doi: 10.3390/s7091731 Lourdes Basabe-Desmonts Frederieke van der Baan Rebecca S. Zimmerman David N. Reinhoudt Mercedes Crego-Calama http://mdpi.com/1424-8220/6/8/1018/ Supramolecular chemistry can be defined as a field of chemistry, which studiesthe complex multi-molecular species formed from molecular components that haverelatively simpler structures. This field has been subject to extensive research over the pastfour decades. This review discusses classification of supramolecules and their application indesign and construction of ion selective sensors. http://mdpi.com/1424-8220/6/8/1018/ Thu, 24 Aug 2006 00:00:00 CEST Sensors 2006-08-24 6 8 Review 1018 1086 1424-8220 Supramolecular Based Membrane Sensors 2006-08-24 doi: 10.3390/s6081018 Mohammad Reza Ganjali Parviz Norouzi Morteza Rezapour Farnoush Faridbod Mohammad Reza Pourjavid http://mdpi.com/1424-8220/6/8/978/ This review discusses different types of artificial tripodal receptors for the selectiverecognition and sensing of cations and anions. Examples on the relationship between structure andselectivity towards cations and anions are described. Furthermore, their applications as potentiometricion sensing are emphasised, along with their potential applications in optical sensors or optodes. http://mdpi.com/1424-8220/6/8/978/ Thu, 24 Aug 2006 00:00:00 CEST Sensors 2006-08-24 6 8 Review 978 1017 1424-8220 Tripodal Receptors for Cation and Anion Sensors 2006-08-24 doi: 10.3390/s6080978 Bambang Kuswandi Nuriman n/a Willem Verboom David N. Reinhoudt http://mdpi.com/1424-8220/6/8/962/ Among different types of calixarenes, the water–soluble ones are of especial interestbecause of their possible applications in biochemical research. In order to elucidate the natureof aqueous solutions of a cationic amphiphilic calixarene, substituted tetrapropoxycalix[4]arene bearing hydrophilic choline groups at the upper rim, we studied vis–spectroscopically the influence of the above system on the acid–base behavior of threeindicator dyes, namely, 2,4-dinitrophenol, bromophenol blue, and N,N/-dioctadecylrhodamine,at constant ionic strength of 0.05 M, maintained with NaCl addition. Simultaneously,‘apparent’ ionization constants, Kaa , of the same dyes were determined in the presence ofcommon cationic surfactant micelles. Within the concentration range from 1.0×10–5 to 0.01 M,the aforementioned water–soluble calixarene displays effects similar to those of micelles ofcetyltrimethylammonium bromide (or chloride). The shifts of the absorption and emissionbands in the visible region, as well as the alterations of the Kaa values against the ‘aqueous’ones appeared to be very similar in aqueous solutions of both calix[4]arene and cationicsurfactant. A conclusion can be made about aggregation (or association), i.e., micelleformation of the cationic calix[4]arene under study. http://mdpi.com/1424-8220/6/8/962/ Thu, 24 Aug 2006 00:00:00 CEST Sensors 2006-08-24 6 8 Article 962 977 1424-8220 The Nature of Aqueous Solutions of a Cationic Calix[4]arene: A Comparative Study of Dye–Calixarene and Dye–Surfactant Interactions 2006-08-24 doi: 10.3390/s6080962 N. O. Mchedlov-Petrossyan L. N. Vilkova N. A. Vodolazkaya A. G. Yakubovskaya R. V. Rodik V. I. Boyko V. I. Kalchenko http://mdpi.com/1424-8220/6/8/954/ A new saccharides sensor based on the TTF-anthracene dyad with two boronicacid (2) groups was designed and synthesized. This new saccharides sensor showsselectivity towards D-glucose while its analogue with one boronic acid group (1) wasreported to bind D-Fructose selectively. Moreover, reaction of compound 2 with uridineinduced even larger fluorescence enhancement under the same condition. http://mdpi.com/1424-8220/6/8/954/ Thu, 24 Aug 2006 00:00:00 CEST Sensors 2006-08-24 6 8 Article 954 961 1424-8220 A New Saccharides and Nnucleosides Sensor Based on Tetrathiafulvalene-anthracene Dyad with Two Boronic Acid Groups 2006-08-24 doi: 10.3390/s6080954 Wei Tan Zhuo Wang Deqing Zhang Daoben Zhu http://mdpi.com/1424-8220/6/8/925/ Luminescent semiconductor nanocrystals or quantum dots (QDs) are a recentlydeveloped class of nanomaterial whose unique photophysical properties are helping tocreate a new generation of robust fluorescent biosensors. QD properties of interest forbiosensing include high quantum yields, broad absorption spectra coupled to narrow sizetunablephotoluminescent emissions and exceptional resistance to both photobleaching andchemical degradation. In this review, we examine the progress in adapting QDs for severalpredominantly in vitro biosensing applications including use in immunoassays, asgeneralized probes, in nucleic acid detection and fluorescence resonance energy transfer(FRET) - based sensing. We also describe several important considerations when workingwith QDs mainly centered on the choice of material(s) and appropriate strategies forattaching biomolecules to the QDs. http://mdpi.com/1424-8220/6/8/925/ Thu, 24 Aug 2006 00:00:00 CEST Sensors 2006-08-24 6 8 Review 925 953 1424-8220 Biosensing with Luminescent Semiconductor Quantum Dots 2006-08-24 doi: 10.3390/s6080925 Kim E. Sapsford Thomas Pons Igor L. Medintz Hedi Mattoussi http://mdpi.com/1424-8220/6/8/915/ A molecularly imprinted polymer for recognising selectively 2,3,7,8-tetrachlorodibenzodioxin (TCDD) was made by a new non-covalent method employing a“dummy” template. The proposed way represents a simplification of a synthetic schemeproposed by Lübke et al.[1] for covalent imprinting. Comparison of extraction yields of thenovel polymer, a non imprinted polymer and an imprinting polymer, prepared by theoriginal procedure demonstrates the binding capacity of the proposed polymer, which is inprinciple applicable to solid phase extraction (SPE) of dioxin. http://mdpi.com/1424-8220/6/8/915/ Thu, 24 Aug 2006 00:00:00 CEST Sensors 2006-08-24 6 8 Article 915 924 1424-8220 Synthesis of a Molecularly Imprinted Polymer for Dioxin 2006-08-24 doi: 10.3390/s6080915 Cosimino Malitesta Rosaria Anna Picca Giuseppe Ciccarella Vito Sgobba Magda Brattoli http://mdpi.com/1424-8220/6/8/901/ Biosensors such as DNA microarrays and microchips are gaining an increasingimportance in medicinal, forensic, and environmental analyses. Such devices are based onthe detection of supramolecular interactions called hybridizations that occur betweencomplementary oligonucleotides, one linked to a solid surface (the probe), and the other oneto be analyzed (the target). This paper focuses on the improvements that hyperbranched andperfectly defined nanomolecules called dendrimers can provide to this methodology. Twomain uses of dendrimers for such purpose have been described up to now; either thedendrimer is used as linker between the solid surface and the probe oligonucleotide, or thedendrimer is used as a multilabeled entity linked to the target oligonucleotide. In the firstcase the dendrimer generally induces a higher loading of probes and an easier hybridization,due to moving away the solid phase. In the second case the high number of localized labels(generally fluorescent) induces an increased sensitivity, allowing the detection of smallquantities of biological entities. http://mdpi.com/1424-8220/6/8/901/ Thu, 24 Aug 2006 00:00:00 CEST Sensors 2006-08-24 6 8 Review 901 914 1424-8220 Uses of Dendrimers for DNA Microarrays 2006-08-24 doi: 10.3390/s6080901 Anne-Marie Caminade Clément Padié Régis Laurent Alexandrine Maraval Jean-Pierre Majoral http://mdpi.com/1424-8220/6/8/892/ In the present paper, the potentiometric response characteristics of ametalloporphyrin-based electrode in o-nitrophenyloctylether (o-NPOE) plasticizedpolyvinyl chloride (PVC) membrane are presented for a set of monovalent anions. Asmembrane ionophore, 5,10,15,20-tetrakis-(4-methoxyphenyl)-porphyrin-Co(II)(CoTMeOPP) was used. To establish the optimum composition of the membrane, differentmolar percents of cationic derivative (mol.% relative to ionophore) were used. Electrodesformulated with membranes containing 1 wt.% ionophore, 66 wt.% o-NPOE, 33 wt.% PVC(plasticizer: PVC = 2:1) and the lipophilic cationic derivative (35 mol%) are shown toexhibit high selectivity for thiocyanate with a near-Nernstian slope in the workingconcentration range of 1.0×10−1–1.0×10−5 M, with a good stability in time. http://mdpi.com/1424-8220/6/8/892/ Thu, 24 Aug 2006 00:00:00 CEST Sensors 2006-08-24 6 8 Article 892 900 1424-8220 A New Composition for Co(II)-porphyrin-based Membranes Used in Thiocyanate-selective Electrodes 2006-08-24 doi: 10.3390/s6080892 Dana Vlascici Eugenia Fagadar-Cosma Otilia Bizerea-Spiridon http://mdpi.com/1424-8220/6/8/874/ This paper describes the electrocatalytic behaviour of a glassy carbon electrode (GCE)modified with cobalt(II)phthalocyanine (CoPc) complex peripherally tetrasubstituted withcobalt(II)tetraphenylporphyrin (CoTPP) complexes via ether linkages (i.e., CoPc-(CoTPP)4). Thefeatures of the immobilised pentamer were interrogated with cyclic voltammetry andelectrochemical impedance spectroscopy (EIS) using [Fe(CN)6]3-/4- as redox probe revealedenhanced electron transfer properties with kapp ≈ 18 x 10-6 cms-1 compared to that of the bareGCE (4.7 x 10-6 cms-1). The viability of this supramolecular complex as a redox mediator for theanodic oxidation and sensitive amperometric determination of hydrazine in alkaline conditions isdescribed. The electrocatalytic oxidation of hydrazine by GCE-CoPc-(CoTPP)4 was characterisedwith satisfactory catalytic current response with low non-Faradaic current (ca. 30 times lowerthan the bare GCE) and at much lower oxidation potential (ca. 300 mV lower than the bareGCE). A mechanism for the studied electrocatalytic reaction was proposed based on thespectrophotometric evidence that revealed the major involvement of the Co(III)/Co(II) redox coupleof the central CoPc species rather than the CoTPP component of the pentamer. Rate constant forthe anodic oxidation of hydrazine was estimated from chronoamperometry as ~ 3x103 M-1s-1. Theproposed amperometric sensor displayed excellent charateristics towards the determination ofhydrazine in 0.2 M NaOH ; such as low overpotentials ( 100 mV vs Ag|AgCl), very fastamperometric response time (1 s), linear concentration range of up to 230 μM, with micromolardetection limit, high sensitivity and stability. http://mdpi.com/1424-8220/6/8/874/ Thu, 24 Aug 2006 00:00:00 CEST Sensors 2006-08-24 6 8 Article 874 891 1424-8220 Anodic Oxidation and Amperometric Sensing of Hydrazine at a Glassy Carbon Electrode Modified with Cobalt (II) Phthalocyanine–cobalt (II) Tetraphenylporphyrin (CoPc- (CoTPP)4) Supramolecular Complex 2006-08-24 doi: 10.3390/s6080874 Kenneth I. Ozoemena http://mdpi.com/1424-8220/6/8/860/ A rigid molecular clip comprising bisphosphonate binding sites and aromaticsidewalls forming an electron-rich cavity is able to distinguish between nucleosides andnucleotides in aqueous solution. Neutral nucleosides as well as antibiotics derived thereofare drawn into the unpolar interior of the cleft and lead to substantial upfield-shifts in the 1HNMR spectrum. Nucleoside drugs can therefore be detected with high selectivity in thepresence of their phosphorylated pendants or nucleic acids. http://mdpi.com/1424-8220/6/8/860/ Thu, 24 Aug 2006 00:00:00 CEST Sensors 2006-08-24 6 8 Article 860 873 1424-8220 Nucleoside Sensing 2006-08-24 doi: 10.3390/s6080860 Michael Fokkens Frank-Gerrit Klärner Thomas Schrader