Self-assembled chemosensors

MIP films, applied to a QCM transducer, have been employed for chiral recognition of the R- and 5-propranolol enantiomers [107]. MIP films were prepared for that purpose by surface grafted photo-radical polymerization. First, a monolayer of 11-mercaptoundecanoic acid was self-assembled on a gold electrode of the quartz resonator. Then, a 2,2 -azobis(2-amidinopropane) hydrochloride initiator (AAPH), was attached to this monolayer. Subsequently, this surface-modified resonator was immersed in an ACN solution containing the MAA functional monomer, enantiomer template and trimethylolpropane trimethacrylate (TRIM) cross-linker. Next, the solution was irradiated with UV light for photopolymerization. The resulting MIP-coated resonator was used for enantioselective determination of the propranolol enantiomers under the batch [107] conditions and the FIA [107] conditions with an aqueous-ACN mixed solvent solution as the carrier. The MIP-QCM chemosensor was enantioselective to 5-propranolol at concentrations exceeding 0.38 mM [107]. 

Herbicides, like demestryn, have been determined using a chemosensor based on the MIP film recognition and capacitive transduction [193, 194]. In this determination, photografting polymerization has been demonstrated as an efficient procedure for fabrication of a capacitive chemosensor. This procedure involved immobilization of an initiator on the electrode. In this case, first, an alkanethiol monolayer was self-assembled on the gold electrode. This monolayer was perfectly dielectric. Then, an MIP film was deposited on top of this monolayer by photo-radical polymerization in the acetone solution with benzophenone, 2-acrylamido-2-methyl-1-propane sulphonic acid, /V./V -iriethylenediacrylamide and demestryn used as the initiator, cross-linker, functional monomer and template, respectively. Subsequently, the template was extracted with methanol. The capacitance decreased by 20% upon binding the demestryn analyte by the MIP film. Similarly, a creatine chemosensor was constructed [194],... 

Mancin F Rampazzo E Tecilla P Tonellato U, Self-assembled fluorescent chemosensors, Chem.-Eur. J., 2006,12, 1844-1854. 

Grandini, P. Mancin, F. Tecilla, P. Scrimin, P. Tonellato, U. Exploiting the Self-Assembly Strategy for the Design of Selective Cu-Ii Ion Chemosensors. Angew. Chem., Int. Ed. 1999, 38,3061-3064... 

Kubo and Nishiyabu describe the use of reversible boronate esterification to build well-ordered microparticles through supramolecular polymerisation of benzene-l,4-diboronic acid with tetraols. When pentaerythritol is used as the tetraol component for self-assembly, thermodynamically stable flower-like microparticles are produced. Surface functionalisation enables formation of nanometal-deposited heterogeneous catalysts and white-light-emissive chemosensors. 

Porphyrins represent an important class of dyes with promising apphcation in many areas, such as optoelectronics, chemosensors and catalysis [6,7]. These dyes exhibit strong absorption and emission in the visible region and show electrochemical activity. The self-assembly of porphyrins is mainly inspired by the photosynthetic systems in nature and is not only important for a better understanding of natural processes, but is also valuable for appUcations in optoelectronic devices. 

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