Catecholamine Detection Using a Functionalized Poly(L-dopa)-Coated Gate Field-Effect Transistor

A highly sensitive catecholamine (CA) sensor was created using a biointerface layer composed of a biopolymer and a potentiometric detection device. For the detection of CAs, 3-aminophenylboronic acid (3-NH2-PBA) was reacted with the carboxyl side chain of L-3,4-dihydroxyphenylalanine (L-dopa, LD) and the PBA-modified L-dopa was directly copolymerized with LD on an Au electrode, resulting in a 3.5 nm thick PBA-modified poly(PBA–LD/LD) layer-coated Au electrode. By connecting the PBA–LD-coated Au electrode to a field-effect transistor (FET), the molecular charge changes at the biointerface of the Au electrode, which was caused by di-ester binding of the PBA–CA complex, were transduced into gate surface potential changes. Effective CAs included LD, dopamine (DA), norepinephrine (NE), and epinephrine (EP). The surface potential of the PBA–LD-coated Au changed after the addition of 40 nM of each CA solution; notably, the PBA–LD-coated Au showed a higher sensitivity to LD because the surface potential change could already be observed after 1 nM of LD was added. The fundamental parameter analyses of the PBA–LD to CA affinity from the surface potential shift against each CA concentration indicated the highest affinity to LD (binding constant (Ks): 1.68 × 106 M–1, maximum surface potential shift (Vmax): 182 mV). Moreover, the limit of detection for each CA was 3.5 nM in LD, 12.0 nM in DA, 7.5 nM in NE, and 12.6 nM in EP. From these results, it is concluded that the poly(PBA–LD/LD)-coated gate FET could become a useful biosensor for neurotransmitters, hormones, and early detection of Parkinson’s disease

Well-designed dopamine-imprinted polymer interface for selective and quantitative dopamine detection among catecholamines using a potentiometric biosensor

We report a well-designed biointerface enabling the selective and quantitative detection of dopamine (DA) using a potentiometric biosensor. To enhance the detection selectivity of DA, a DA-templated molecularly imprinted polymer (DA–MIP) was synthesized on the extended Au gate electrode of a field-effect transistor (FET) biosensor. For a quantitative DA analysis, the thickness of the DA–MIP was controlled to ca. 60 nm by surface-initiated atom transfer radical polymerization (SI-ATRP). In this process, the DA–MIP was copolymerized with vinylphenylboronic acid (vinyl-PBA), inducing molecular charges at the biointerface of the FET gate electrode. These charges were generated by the diol-binding between PBA and dopamine (a catecholamine), and were directly detected as a change in surface potential. In fact, the surface potential at the gate of the DA–MIP-coated FET responded significantly to DA added at concentrations ranging from 40 nM to μM, whereas that of a non-imprinted polymer (NIP)-coated FET hardly changed over this range. Moreover, by measuring the kinetic parameters and electrochemical properties of well-designed devices with various added catecholamines, we confirmed that the DA–MIP-coated FET biosensor selectively and quantitatively detects DA

The [2+2] Cycloaddition-Retroelectrocyclization (CA-RE) Click Reaction: Facile Access to Molecular and Polymeric Push-Pull Chromophores

ISSN:1433-7851ISSN:1521-3773ISSN:0570-083

Postfunctionalization of Alkyne-Linked Conjugated Carbazole Polymer by Thermal Addition Reaction of Tetracyanoethylene

The postfunctionalization of the main chain alkyne moieties of carbazole containing poly(arylenebutadiynylene)s was attempted by using a high yielding addition reaction between electron rich alkynes and a strong acceptor molecule, tetracyanoethylene (TCNE). After successful postfunctionalization, the polymer band gap decreased due to the intramolecular donor-acceptor interactions. The resulting donor-acceptor alternating polymer showed a very broad charge-transfer band in the visible region as well as redox activities in both anodic and cathodic directions. The optical band gap showed good agreement with the electrochemical band gap. Furthermore, the thermal stability was enhanced after postfunctionalization. These features of the donor-acceptor alternating polymer are expected to be useful for high performance activities in organic solar cell applications