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Various forms of zinc oxide (ZnO) are frequently used in the design of optical and electrochemical sensors. However, the optical and electrochemical properties of ZnO should be properly adjusted depending on the application area. Therefore, in this work, we have investigated changing/tuning the properties of ZnO by depositing a layer of polydopamine (PDA) on its surface. In order to perform this investigation, the surface of fluorine-doped tin oxide (FTO) was modified with the layer of ZnO nanorods and PDA. ZnO nanorods were synthesized by hydrothermal synthesis technique, and after the synthesis, they were coated with polydopamine exploiting the self-polymerization of dopamine. The nanostructures were investigated by using electrochemical and optical methods. Electrochemical impedance spectroscopy measurements showed that electrochemical properties of FTO-ZnO and FTO-ZnO-PDA nanostructures could be changed by the variation of both—applied electrical potential and/or exposition towards lighting. Interaction between ZnO-PDA and bovine serum albumin (BSA) molecules has been investigated by (photo)electrochemical and photoluminescence methods. A mechanism of possible interaction between BSA and the ZnO-PDA surface has been proposed. [ABSTRACT FROM AUTHOR]

Various forms of zinc oxide (ZnO) are frequently used in the design of optical and electrochemical sensors. However, the optical and electrochemical properties of ZnO should be properly adjusted depending on the application area. Therefore, in this work, we have investigated changing/tuning the properties of ZnO by depositing a layer of polydopamine (PDA) on its surface. In order to perform this investigation, the surface of fluorine-doped tin oxide (FTO) was modified with the layer of ZnO nanorods and PDA. ZnO nanorods were synthesized by hydrothermal synthesis technique, and after the synthesis, they were coated with polydopamine exploiting the self-polymerization of dopamine. The nanostructures were investigated by using electrochemical and optical methods. Electrochemical impedance spectroscopy measurements showed that electrochemical properties of FTO-ZnO and FTO-ZnO-PDA nanostructures could be changed by the variation of both—applied electrical potential and/or exposition towards lighting. Interaction between ZnO-PDA and bovine serum albumin (BSA) molecules has been investigated by (photo)electrochemical and photoluminescence methods. A mechanism of possible interaction between BSA and the ZnO-PDA surface has been proposed.

A novel potentiometric pH sensor based on polydopamine films coated on a carbon nano-onion conductive surface is introduced. Glassy carbon electrodes containing a carbon nano-onion layer were modified by electropolymerization and self-polymerization of dopamine. The modified surfaces were characterized by ESEM, RAMAN spectroscopy and cyclic voltammetry. The modified electrodes displayed an almost Nernstian potentiometric response over the pH range 2–10. Furthermore, the pH sensors exhibit a fast and reversible behavior toward variations of pH and negligible interference effects from monovalent cations. The sensors showed an excellent correspondence between the pH values obtained using the GCE/CNO/PDA electrodes and those measured with glass electrodes and were applied to the analysis of real samples covering a wide pH range from 2.2 to 8.3. The analytical performance is comparable to other reported devices based on electropolymerized amines over graphite and noble metal electrodes. Their reproducible and stable response and their ease of fabrication is very promising for the miniaturization and integration of pH sensors in (bio)analytical devices. [ABSTRACT FROM AUTHOR]

A molecularly imprinted polymer (MIP) was prepared by self-polymerization of dopamine in the presence of bovine hemoglobin (BHb) and then deposited on the surface of an electrode modified with gold nanoparticles (AuNPs). Scanning electron microscopy, cyclic voltammetry, and differential pulse voltammetry were employed to characterize the modified electrode using the hexacyanoferrate redox system as an electroactive probe. The effects of BHb concentration, dopamine concentration, and polymerization time were optimized. Under optimized conditions, the modified electrode selectively recognizes BHb even in the presence of other proteins. The peak current for hexacyanoferrate, typically measured at + 0.17 V (vs. SCE), depends on the concentration of BHb in the 1.0 × 10 to 1.0 × 10 mg mL range. Due to the ease of preparation and tight adherence of polydopamine to various support materials, the present strategy conceivably also provides a platform for the recognition and detection of other proteins. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The synthesis of indolo[3,2- b ]carbazole-based mono- and dihydrazones with reactive vinylbenzyl or vinyloxyethyl functional groups at the nitrogen atom of hydrazine moiety is reported. The thermal, optical, photophysical, electrochemical and photoelectrical properties of the synthesized compounds are described. They exhibit moderate thermal stability with 5% weight loss temperatures ranging from 273 to 343 °C. Self-polymerization of the monomers with vinylbenzyl functional groups starts at around 180 °C. The values of ionization potentials of the compounds measured by cyclic voltammetry are in the range of 4.94–5.00 eV and those estimated by electron photoemission in air range from 4.99 to 5.21 eV. Electron affinities range from −2.28 to −2.23 eV. The molecular structure of these hydrazones allows stable amorphous films to be prepared and the hole drift mobilities of the films exceed 10 −3 cm 2 /V s at high electric fields. [ABSTRACT FROM AUTHOR]