100% coverage 60% 0.05 mM MFI / a.u. c /mM 0.05 mM

No abstract

Effective recognition of enzymatically active tetrameric acetylcholinesterase (AChE) was accomplished by a hybrid nanofilm composed of a propidium-terminated self-assembled monolayer (Prop-SAM) which binds AChE via its peripheral anionic site (PAS) and an ultra-thin electrosynthesized molecularly imprinted polymer (MIP) cover layer of a novel carboxylate-modified derivative of 3,4-propylenedioxythiophene. The rebinding of the AChE to the MIP/Prop-SAM nanofilm covered electrode was detected by measuring in situ the enzymatic activity. The oxidative current of the released thiocholine was dependent on the AChE concentration from ca. 0.04 µM to 0.4 µM. An imprinting factor of 9.9 was obtained for the hybrid MIP, which is among the best values reported for protein imprinting.The dissociation constant characterizing the strength of the MIP-AChE binding was 4.2 ×10 −7 M indicating the dominant role of the PAS-Prop-SAM interaction, while the benefit of the MIP nanofilm covering the Prop-SAM layer was the effective suppression of the cross-reactivity towards competing proteins as compared with the Prop-SAM. The threefold selectivity gain provided by (i) the "shapespecific" MIP filter, (ii) the propidium-SAM, (iii) signal generation only by the AChE bound to the nanofilm show promise for assessing AChE activity levels in CSF.

A sensitive electrochemical MIP sensor for salbutamol detection based on a graphene nanocomposite modified screen-printed carbon electrode was successfully demonstrated. Insertion of the graphene/ PEDOT:PSS layer prior to the MIP was aimed at enhancing the sensitivity of the sensor. Selection of a functional monomer was carried out using 1 H-NMR titration and a computational calculation was used to further investigate the template-monomer interactions. The MIP layer was constructed on top of the highly conductive nanocomposite by co-electropolymerization of 3-aminophenylboronic acid and o-phenylenediamine in the presence of salbutamol. Using differential pulse voltammetry under optimal conditions, a linear response in the range of 1 nM to 1.2 mM, with an exceptional detection limit of 100 pM (S/N ¼ 3) was obtained. The established sensor exhibited good reproducibility, reusability and stability. Additionally, good selectivity in discriminating salbutamol from other structurally related compounds could also be realized. Determination of salbutamol in real swine meat and feed samples was also successfully carried out with good recovery results.

A novel strategy to prepare a surface confined molecularly imprinted polymer (MIP) film directly on a transducer surface for protein sensing is achieved by combining interaction with a natural binding receptor and binding to a fully synthetic MIP. A thiolated oligoethyleneglycol (OEG)/mannose conjugate is first self‐assembled on the transducer surface. Then the carbohydrate binding protein, concanavalin A (ConA), is “vectorially” immobilized as a submonolayer on the underlying mannose modified surface. Afterwards, an ultrathin polyscopoletin film with the thickness comparable to that of the protein is electrodeposited on the top. This architecture ensures that the target is confined to the film surface. The resulting functional material shows an approximately 20‐fold higher affinity than that obtained from the mannose self‐assembled monolayer. This result shows a synergism between multivalent binding of the natural sugar ligand and the non‐covalent interactions of the target within the MIP cavities. Recognition capability of the film is characterized by a real‐time measurement using quartz crystal microbalance. In comparison to the non‐imprinted film, the imprinted film reveals 8.6 times higher binding capacity towards ConA. High discrimination towards the target protein's homologues shows size and shape specificity of the imprint.